Bug 10846 - Slow write on LSISAS1068E (SAS6/iR) on kernel >= 2.6.22
Summary: Slow write on LSISAS1068E (SAS6/iR) on kernel >= 2.6.22
Status: REJECTED INVALID
Alias: None
Product: SCSI Drivers
Classification: Unclassified
Component: Other (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: scsi_drivers-other
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2008-06-02 07:57 UTC by Dominique LALOT
Modified: 2008-06-13 00:52 UTC (History)
2 users (show)

See Also:
Kernel Version: 2.6.24-16
Subsystem:
Regression: ---
Bisected commit-id:

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Description Dominique LALOT 2008-06-02 07:57:42 UTC 
Latest working kernel version:
2.6.21.7

Earliest failing kernel version:
2.6.22.1 till 2.6.24

debian-test:/usr/src# cat /proc/version
Linux version 2.6.22.19 (root@debian-test.pr.univmed.fr) (gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)) #1 SMP Fri May 30 19:53:56 CEST 2008


Distribution:
Ubuntu server 8.04 / Debian Lenny

Hardware Environment:
debian-test:/usr/src/linux# lspci -vvv
00:00.0 Host bridge: Intel Corporation 5000P Chipset Memory Controller Hub (rev 92)
        Subsystem: Intel Corporation Unknown device 8086
        Control: I/O- Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 0
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable-
                Address: fee00000  Data: 0000
        Capabilities: [6c] Express Root Port (Slot-) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 0
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:02.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x4 Port 2 (rev 92) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=00, secondary=01, subordinate=07, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: d8000000-ddffffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable+
                Address: feeff00c  Data: 41c9
        Capabilities: [6c] Express Root Port (Slot-) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 2
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:03.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x4 Port 3 (rev 92) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=00, secondary=08, subordinate=08, sec-latency=0
        I/O behind bridge: 0000e000-0000efff
        Memory behind bridge: de100000-de2fffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable+
                Address: feeff00c  Data: 41d1
        Capabilities: [6c] Express Root Port (Slot-) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 256 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 3
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:04.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x8 Port 4-5 (rev 92) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=00, secondary=09, subordinate=09, sec-latency=0
        I/O behind bridge: 0000d000-0000dfff
        Memory behind bridge: de300000-de3fffff
        Prefetchable memory behind bridge: 00000000de500000-00000000de5fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable+
                Address: feeff00c  Data: 41d9
        Capabilities: [6c] Express Root Port (Slot+) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 256 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x8, ASPM L0s, Port 4
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
                Slot: AtnBtn- PwrCtrl- MRL- AtnInd- PwrInd- HotPlug- Surpise-
                Slot: Number 1, PowerLimit 25.000000
                Slot: Enabled AtnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq-
                Slot: AttnInd Off, PwrInd Off, Power-
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:05.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x4 Port 5 (rev 92) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=00, secondary=0a, subordinate=0a, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: fff00000-000fffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable+
                Address: feeff00c  Data: 41e1
        Capabilities: [6c] Express Root Port (Slot+) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 5
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes Disabled CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x0
                Slot: AtnBtn- PwrCtrl- MRL- AtnInd- PwrInd- HotPlug- Surpise-
                Slot: Number 2, PowerLimit 25.000000
                Slot: Enabled AtnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq-
                Slot: AttnInd Off, PwrInd Off, Power-
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:06.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x8 Port 6-7 (rev 92) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=00, secondary=0b, subordinate=0b, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: fff00000-000fffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable+
                Address: feeff00c  Data: 41e9
        Capabilities: [6c] Express Root Port (Slot+) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x8, ASPM L0s, Port 6
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes Disabled CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
                Slot: AtnBtn- PwrCtrl- MRL- AtnInd- PwrInd- HotPlug- Surpise-
                Slot: Number 3, PowerLimit 25.000000
                Slot: Enabled AtnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq-
                Slot: AttnInd Off, PwrInd Off, Power-
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:07.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x4 Port 7 (rev 92) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=00, secondary=0c, subordinate=0c, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: fff00000-000fffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit- Queue=0/1 Enable+
                Address: feeff00c  Data: 4132
        Capabilities: [6c] Express Root Port (Slot+) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s unlimited, L1 unlimited
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 7
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes Disabled CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x0
                Slot: AtnBtn- PwrCtrl- MRL- AtnInd- PwrInd- HotPlug- Surpise-
                Slot: Number 4, PowerLimit 25.000000
                Slot: Enabled AtnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq-
                Slot: AttnInd Off, PwrInd Off, Power-
                Root: Correctable- Non-Fatal- Fatal- PME-
        Capabilities: [100] Advanced Error Reporting

00:10.0 Host bridge: Intel Corporation 5000 Series Chipset Error Reporting Registers (rev 92)
        Subsystem: Dell Unknown device 0208
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:10.1 Host bridge: Intel Corporation 5000 Series Chipset Error Reporting Registers (rev 92)
        Subsystem: Dell Unknown device 0208
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:10.2 Host bridge: Intel Corporation 5000 Series Chipset Error Reporting Registers (rev 92)
        Subsystem: Dell Unknown device 0208
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:11.0 Host bridge: Intel Corporation 5000 Series Chipset Reserved Registers (rev 92)
        Subsystem: Intel Corporation Unknown device 8086
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:13.0 Host bridge: Intel Corporation 5000 Series Chipset Reserved Registers (rev 92)
        Subsystem: Intel Corporation Unknown device 8086
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:15.0 Host bridge: Intel Corporation 5000 Series Chipset FBD Registers (rev 92)
        Subsystem: Intel Corporation Unknown device 8086
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:16.0 Host bridge: Intel Corporation 5000 Series Chipset FBD Registers (rev 92)
        Subsystem: Intel Corporation Unknown device 8086
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

00:1d.0 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #1 (rev 09) (prog-if 00 [UHCI])
        Subsystem: Dell Unknown device 0208
        Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0
        Interrupt: pin A routed to IRQ 20
        Region 4: I/O ports at bc80 [size=32]

00:1d.1 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #2 (rev 09) (prog-if 00 [UHCI])
        Subsystem: Dell Unknown device 0208
        Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0
        Interrupt: pin B routed to IRQ 21
        Region 4: I/O ports at bca0 [size=32]

00:1d.2 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #3 (rev 09) (prog-if 00 [UHCI])
        Subsystem: Dell Unknown device 0208
        Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0
        Interrupt: pin C routed to IRQ 20
        Region 4: I/O ports at bcc0 [size=32]

00:1d.7 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset EHCI USB2 Controller (rev 09) (prog-if 20 [EHCI])
        Subsystem: Dell Unknown device 0208
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0
        Interrupt: pin A routed to IRQ 20
        Region 0: Memory at de0ff800 (32-bit, non-prefetchable) [size=1K]
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Debug port

00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d9) (prog-if 01 [Subtractive decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0
        Bus: primary=00, secondary=0d, subordinate=0d, sec-latency=32
        I/O behind bridge: 0000c000-0000cfff
        Memory behind bridge: de400000-de4fffff
        Prefetchable memory behind bridge: 00000000d0000000-00000000d7ffffff
        Secondary status: 66MHz- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA- VGA+ MAbort- >Reset- FastB2B-
        Capabilities: [50] Subsystem: Gammagraphx, Inc. Unknown device 0000

00:1f.0 ISA bridge: Intel Corporation 631xESB/632xESB/3100 Chipset LPC Interface Controller (rev 09)
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0

01:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express Upstream Port (rev 01) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=01, secondary=02, subordinate=06, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: da000000-ddffffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [44] Express Upstream Port IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s <64ns, L1 <1us
                Device: AtnBtn- AtnInd- PwrInd-
                Device: SlotPowerLimit 0.000000
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                Device: MaxPayload 128 bytes, MaxReadReq 4096 bytes
                Link: Supported Speed 2.5Gb/s, Width x8, ASPM L0s, Port 0
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [70] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [80] Subsystem: Gammagraphx, Inc. Unknown device 0000
        Capabilities: [100] Advanced Error Reporting

01:00.3 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express to PCI-X Bridge (rev 01) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=01, secondary=07, subordinate=07, sec-latency=64
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: fff00000-000fffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz+ FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [44] Express PCI/PCI-X Bridge IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s <64ns, L1 <1us
                Device: AtnBtn- AtnInd- PwrInd-
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                Device: MaxPayload 128 bytes, MaxReadReq 256 bytes
                Link: Supported Speed 2.5Gb/s, Width x8, ASPM L0s, Port 0
                Link: Latency L0s unlimited, L1 unlimited
                Link: ASPM Disabled CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [6c] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [80] Subsystem: Gammagraphx, Inc. Unknown device 0000
        Capabilities: [d8] PCI-X bridge device
                Secondary Status: 64bit+ 133MHz+ SCD- USC- SCO- SRD- Freq=100MHz
                Status: Dev=00:00.3 64bit- 133MHz- SCD- USC- SCO- SRD-
                Upstream: Capacity=65535 CommitmentLimit=65535
                Downstream: Capacity=65535 CommitmentLimit=65535
        Capabilities: [100] Advanced Error Reporting

02:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express Downstream Port E1 (rev 01) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=02, secondary=03, subordinate=04, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: dc000000-ddffffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [44] Express Downstream Port (Slot-) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s <64ns, L1 <1us
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                Device: MaxPayload 128 bytes, MaxReadReq 4096 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 0
                Link: Latency L0s <512ns, L1 unlimited
                Link: ASPM Disabled CommClk+ ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [60] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
                Address: 00000000feeff00c  Data: 413a
        Capabilities: [70] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [80] Subsystem: Gammagraphx, Inc. Unknown device 0000
        Capabilities: [100] Advanced Error Reporting

02:01.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express Downstream Port E2 (rev 01) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=02, secondary=05, subordinate=06, sec-latency=0
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: da000000-dbffffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [44] Express Downstream Port (Slot-) IRQ 0
                Device: Supported: MaxPayload 256 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s <64ns, L1 <1us
                Device: Errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                Device: MaxPayload 128 bytes, MaxReadReq 4096 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 0
                Link: Latency L0s <512ns, L1 unlimited
                Link: ASPM Disabled CommClk+ ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [60] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
                Address: 00000000feeff00c  Data: 4142
        Capabilities: [70] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [80] Subsystem: Gammagraphx, Inc. Unknown device 0000
        Capabilities: [100] Advanced Error Reporting

03:00.0 PCI bridge: Broadcom EPB PCI-Express to PCI-X Bridge (rev c3) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=03, secondary=04, subordinate=04, sec-latency=64
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: dc000000-ddffffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [60] Express PCI/PCI-X Bridge IRQ 0
                Device: Supported: MaxPayload 128 bytes, PhantFunc 0, ExtTag+
                Device: Latency L0s <64ns, L1 <1us
                Device: AtnBtn- AtnInd- PwrInd-
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s L1, Port 0
                Link: Latency L0s <1us, L1 <4us
                Link: ASPM Disabled CommClk+ ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [90] PCI-X bridge device
                Secondary Status: 64bit+ 133MHz+ SCD- USC- SCO- SRD- Freq=133MHz
                Status: Dev=03:00.0 64bit- 133MHz- SCD- USC- SCO- SRD-
                Upstream: Capacity=0 CommitmentLimit=0
                Downstream: Capacity=0 CommitmentLimit=0
        Capabilities: [b0] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=1 PME-
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [14c] Power Budgeting
        Capabilities: [160] Device Serial Number c0-88-3d-fe-ff-4f-1e-00

04:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5708S Gigabit Ethernet (rev 12)
        Subsystem: Dell Unknown device 0208
        Control: I/O- Mem+ BusMaster+ SpecCycle+ MemWINV+ VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 64 (16000ns min), Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 211
        Region 0: Memory at dc000000 (64-bit, non-prefetchable) [size=32M]
        Capabilities: [40] PCI-X non-bridge device
                Command: DPERE- ERO- RBC=512 OST=8
                Status: Dev=04:00.0 64bit+ 133MHz+ SCD- USC- DC=simple DMMRBC=512 DMOST=8 DMCRS=32 RSCEM- 266MHz- 533MHz-
        Capabilities: [48] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=1 PME-
        Capabilities: [50] Vital Product Data
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
                Address: 00000000feeff00c  Data: 417a

05:00.0 PCI bridge: Broadcom EPB PCI-Express to PCI-X Bridge (rev c3) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Bus: primary=05, secondary=06, subordinate=06, sec-latency=64
        I/O behind bridge: 0000f000-00000fff
        Memory behind bridge: da000000-dbffffff
        Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
        BridgeCtl: Parity+ SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
        Capabilities: [60] Express PCI/PCI-X Bridge IRQ 0
                Device: Supported: MaxPayload 128 bytes, PhantFunc 0, ExtTag+
                Device: Latency L0s <64ns, L1 <1us
                Device: AtnBtn- AtnInd- PwrInd-
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                Device: MaxPayload 128 bytes, MaxReadReq 128 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s L1, Port 0
                Link: Latency L0s <1us, L1 <4us
                Link: ASPM Disabled CommClk+ ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [90] PCI-X bridge device
                Secondary Status: 64bit+ 133MHz+ SCD- USC- SCO- SRD- Freq=133MHz
                Status: Dev=05:00.0 64bit- 133MHz- SCD- USC- SCO- SRD-
                Upstream: Capacity=0 CommitmentLimit=0
                Downstream: Capacity=0 CommitmentLimit=0
        Capabilities: [b0] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=1 PME-
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [14c] Power Budgeting
        Capabilities: [160] Device Serial Number c2-88-3d-fe-ff-4f-1e-00

06:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5708S Gigabit Ethernet (rev 12)
        Subsystem: Dell Unknown device 0208
        Control: I/O- Mem+ BusMaster+ SpecCycle+ MemWINV+ VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 64 (16000ns min), Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 18
        Region 0: Memory at da000000 (64-bit, non-prefetchable) [size=32M]
        Capabilities: [40] PCI-X non-bridge device
                Command: DPERE- ERO- RBC=512 OST=8
                Status: Dev=06:00.0 64bit+ 133MHz+ SCD- USC- DC=simple DMMRBC=512 DMOST=8 DMCRS=32 RSCEM- 266MHz- 533MHz-
        Capabilities: [48] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=1 PME-
        Capabilities: [50] Vital Product Data
        Capabilities: [58] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable-
                Address: 8ba7fdde142ffbd8  Data: 6ddc

08:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1068E PCI-Express Fusion-MPT SAS (rev 08)
        Subsystem: Dell Unknown device 1f0f
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 17
        Region 0: I/O ports at ec00 [size=256]
        Region 1: Memory at de2ec000 (64-bit, non-prefetchable) [size=16K]
        Region 3: Memory at de2f0000 (64-bit, non-prefetchable) [size=64K]
        Expansion ROM at de100000 [disabled] [size=1M]
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [68] Express Endpoint IRQ 0
                Device: Supported: MaxPayload 4096 bytes, PhantFunc 0, ExtTag+
                Device: Latency L0s <64ns, L1 <1us
                Device: AtnBtn- AtnInd- PwrInd-
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 256 bytes, MaxReadReq 512 bytes
                Link: Supported Speed 2.5Gb/s, Width x8, ASPM L0s L1, Port 0
                Link: Latency L0s <64ns, L1 <1us
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [98] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable-
                Address: 0000000000000000  Data: 0000
        Capabilities: [b0] MSI-X: Enable- Mask- TabSize=1
                Vector table: BAR=1 offset=00002000
                PBA: BAR=1 offset=00003000
        Capabilities: [100] Advanced Error Reporting

09:00.0 Fibre Channel: QLogic Corp. QLA2432 Fibre Channel Adapter (rev 03)
        Subsystem: QLogic Corp. Unknown device 015b
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 18
        Region 0: I/O ports at d800 [size=256]
        Region 1: Memory at de3f8000 (64-bit, non-prefetchable) [size=16K]
        Expansion ROM at de300000 [disabled] [size=256K]
        Capabilities: [44] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [4c] Express Endpoint IRQ 0
                Device: Supported: MaxPayload 1024 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s <4us, L1 <1us
                Device: AtnBtn+ AtnInd+ PwrInd+
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 256 bytes, MaxReadReq 2048 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 0
                Link: Latency L0s <4us, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [64] Message Signalled Interrupts: Mask- 64bit+ Queue=0/4 Enable-
                Address: 0000000000000000  Data: 0000
        Capabilities: [74] Vital Product Data
        Capabilities: [7c] MSI-X: Enable+ Mask- TabSize=16
                Vector table: BAR=1 offset=00002000
                PBA: BAR=1 offset=00003000
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [138] Power Budgeting

09:00.1 Fibre Channel: QLogic Corp. QLA2432 Fibre Channel Adapter (rev 03)
        Subsystem: QLogic Corp. Unknown device 015b
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin B routed to IRQ 19
        Region 0: I/O ports at dc00 [size=256]
        Region 1: Memory at de3fc000 (64-bit, non-prefetchable) [size=16K]
        Expansion ROM at de500000 [disabled] [size=256K]
        Capabilities: [44] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [4c] Express Endpoint IRQ 0
                Device: Supported: MaxPayload 1024 bytes, PhantFunc 0, ExtTag-
                Device: Latency L0s <4us, L1 <1us
                Device: AtnBtn+ AtnInd+ PwrInd+
                Device: Errors: Correctable- Non-Fatal- Fatal+ Unsupported-
                Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
                Device: MaxPayload 256 bytes, MaxReadReq 2048 bytes
                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 0
                Link: Latency L0s <4us, L1 unlimited
                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
                Link: Speed 2.5Gb/s, Width x4
        Capabilities: [64] Message Signalled Interrupts: Mask- 64bit+ Queue=0/4 Enable-
                Address: 0000000000000000  Data: 0000
        Capabilities: [74] Vital Product Data
        Capabilities: [7c] MSI-X: Enable+ Mask- TabSize=16
                Vector table: BAR=1 offset=00002000
                PBA: BAR=1 offset=00003000
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [138] Power Budgeting

0d:04.0 VGA compatible controller: ATI Technologies Inc ES1000 (rev 02) (prog-if 00 [VGA])
        Subsystem: Dell Unknown device 0208
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping+ SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 32 (2000ns min), Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 6
        Region 0: Memory at d0000000 (32-bit, prefetchable) [size=128M]
        Region 1: I/O ports at cc00 [size=256]
        Region 2: Memory at de4f0000 (32-bit, non-prefetchable) [size=64K]
        [virtual] Expansion ROM at de400000 [disabled] [size=128K]
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-


debian-test:/usr/src/linux-2.6.22.19/scripts# cat /proc/modules
xt_length 2048 0 - Live 0xf8dc1000
ipt_ttl 1984 0 - Live 0xf8dbf000
xt_tcpmss 2304 0 - Live 0xf8dbd000
iptable_mangle 2912 0 - Live 0xf8dbb000
iptable_filter 3104 0 - Live 0xf8db9000
xt_multiport 3200 0 - Live 0xf8daf000
xt_limit 2720 0 - Live 0xf8923000
ipt_tos 1760 0 - Live 0xf8d9c000
ipt_REJECT 4128 0 - Live 0xf8db6000
ip_tables 12420 2 iptable_mangle,iptable_filter, Live 0xf8db1000
x_tables 14564 8 xt_length,ipt_ttl,xt_tcpmss,xt_multiport,xt_limit,ipt_tos,ipt_REJECT,ip_tables, Live 0xf8d90000
button 8080 0 - Live 0xf8da9000
ac 5348 0 - Live 0xf8d99000
battery 10116 0 - Live 0xf8d95000
ipmi_devintf 9096 4 - Live 0xf8bc6000
ipmi_si 39308 2 - Live 0xf8d9e000
ipmi_msghandler 35024 2 ipmi_devintf,ipmi_si, Live 0xf8c28000
ipv6 236676 22 - Live 0xf8dd7000
mptctl 23460 2 - Live 0xf8c3c000
loop 16996 0 - Live 0xf8be1000
sg 32764 0 - Live 0xf8c33000
serio_raw 6852 0 - Live 0xf8bca000
tsdev 8160 0 - Live 0xf88d6000
joydev 9696 0 - Live 0xf8bcd000
psmouse 36112 0 - Live 0xf8c14000
shpchp 31316 0 - Live 0xf8c1f000
rtc 12568 0 - Live 0xf8c0f000
pci_hotplug 29408 1 shpchp, Live 0xf8c06000
sr_mod 16548 0 - Live 0xf8bdb000
cdrom 33056 1 sr_mod, Live 0xf8bd1000
evdev 9472 0 - Live 0xf8bc2000
ext3 121704 2 - Live 0xf8be7000
jbd 55528 1 ext3, Live 0xf8950000
mbcache 8516 1 ext3, Live 0xf88db000
dm_mirror 20896 0 - Live 0xf8949000
dm_snapshot 17060 0 - Live 0xf8943000
dm_mod 52384 7 dm_mirror,dm_snapshot, Live 0xf8bb4000
ide_generic 1312 0 [permanent], Live 0xf8832000
sd_mod 27360 3 - Live 0xf893b000
usbhid 25952 0 - Live 0xf8933000
usb_storage 75328 0 - Live 0xf89da000
ide_core 112164 2 ide_generic,usb_storage, Live 0xf89bd000
mptsas 27496 2 - Live 0xf891b000
qla2xxx 144388 0 - Live 0xf895f000
mptscsih 21408 1 mptsas, Live 0xf8914000
firmware_class 9728 1 qla2xxx, Live 0xf8856000
mptbase 52768 3 mptctl,mptsas,mptscsih, Live 0xf8925000
ehci_hcd 31340 0 - Live 0xf88b6000
scsi_transport_sas 27872 1 mptsas, Live 0xf8842000
scsi_transport_fc 33924 1 qla2xxx, Live 0xf885d000
uhci_hcd 22992 0 - Live 0xf884a000
usbcore 125736 5 usbhid,usb_storage,ehci_hcd,uhci_hcd, Live 0xf88f4000
bnx2 151256 0 - Live 0xf8890000
scsi_mod 136652 10 mptctl,sg,sr_mod,sd_mod,usb_storage,mptsas,qla2xxx,mptscsih,scsi_transport_sas,scsi_transport_fc, Live 0xf886d000
thermal 13576 0 - Live 0xf8834000
processor 31176 1 thermal, Live 0xf8839000
fan 4964 0 - Live 0xf882b000


debian-test:/usr/src/linux# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: SEAGATE  Model: ST9146802SS      Rev: S229
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi0 Channel: 00 Id: 01 Lun: 00
  Vendor: SEAGATE  Model: ST9146802SS      Rev: S229
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi0 Channel: 01 Id: 00 Lun: 00
  Vendor: Dell     Model: VIRTUAL DISK     Rev: 1028
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi3 Channel: 00 Id: 00 Lun: 00
  Vendor:          Model: Virtual CDROM    Rev: 1.00
  Type:   CD-ROM                           ANSI  SCSI revision: 00
Host: scsi4 Channel: 00 Id: 00 Lun: 00
  Vendor:          Model: Virtual Floppy   Rev: 1.00
  Type:   Direct-Access                    ANSI  SCSI revision: 00


Software Environment:

debian-test:/usr/src/linux-2.6.22.19/scripts# ./ver_linux
If some fields are empty or look unusual you may have an old version.
Compare to the current minimal requirements in Documentation/Changes.

Linux debian-test.pr.univmed.fr 2.6.22.19 #1 SMP Fri May 30 19:53:56 CEST 2008 i686 GNU/Linux

Gnu C                  4.1.2
Gnu make               3.81
binutils               2.17
util-linux             2.12r
mount                  2.12r
module-init-tools      3.3-pre2
e2fsprogs              1.40-WIP
Linux C Library        2.3.6
Dynamic linker (ldd)   2.3.6
Procps                 3.2.7
Net-tools              1.60
Console-tools          0.2.3
Sh-utils               5.97
udev                   105
Modules Loaded         xt_length ipt_ttl xt_tcpmss iptable_mangle iptable_filter xt_multiport xt_limit ipt_tos ipt_REJECT ip_tables x_tables button ac battery ipmi_devintf ipmi_si ipmi_msghandler ipv6 mptctl loop sg serio_raw tsdev joydev psmouse shpchp rtc pci_hotplug sr_mod cdrom evdev ext3 jbd mbcache dm_mirror dm_snapshot dm_mod ide_generic sd_mod usbhid usb_storage ide_core mptsas qla2xxx mptscsih firmware_class mptbase ehci_hcd scsi_transport_sas scsi_transport_fc uhci_hcd usbcore bnx2 scsi_mod thermal processor fan

debian-test:/usr/src/linux-2.6.22.19/scripts# cat /proc/ioports
0000-001f : dma1
0020-0021 : pic1
0040-0043 : timer0
0050-0053 : timer1
0060-006f : keyboard
0070-0077 : rtc
0080-008f : dma page reg
00a0-00a1 : pic2
00c0-00df : dma2
00f0-00ff : fpu
03c0-03df : vga+
03f8-03ff : serial
0800-087f : pnp 00:05
  0800-0803 : ACPI PM1a_EVT_BLK
  0804-0805 : ACPI PM1a_CNT_BLK
  0808-080b : ACPI PM_TMR
  0810-0815 : ACPI CPU throttle
  0828-082f : ACPI GPE0_BLK
  0850-0850 : ACPI PM2_CNT_BLK
0880-08bf : pnp 00:05
08c0-08df : pnp 00:05
08e0-08e3 : pnp 00:05
0900-0900 : pnp 00:05
0c00-0c7f : pnp 00:05
0ca0-0ca1 : pnp 00:05
0ca2-0ca2 : pnp 00:06
  0ca2-0ca2 : ipmi_si
0ca3-0ca3 : pnp 00:06
  0ca3-0ca3 : ipmi_si
0ca4-0caf : pnp 00:05
0cf8-0cff : PCI conf1
bc80-bc9f : 0000:00:1d.0
  bc80-bc9f : uhci_hcd
bca0-bcbf : 0000:00:1d.1
  bca0-bcbf : uhci_hcd
bcc0-bcdf : 0000:00:1d.2
  bcc0-bcdf : uhci_hcd
c000-cfff : PCI Bus #0d
  cc00-ccff : 0000:0d:04.0
d000-dfff : PCI Bus #09
  d800-d8ff : 0000:09:00.0
    d800-d8ff : qla2xxx
  dc00-dcff : 0000:09:00.1
    dc00-dcff : qla2xxx
e000-efff : PCI Bus #08
  ec00-ecff : 0000:08:00.0

debian-test:/usr/src/linux-2.6.22.19/scripts# cat /proc/iomem
00000000-0009ffff : System RAM
  00000000-00000000 : Crash kernel
000a0000-000bffff : Video RAM area
000c0000-000c8fff : Video ROM
000c9000-000c9fff : Adapter ROM
000ca000-000cbdff : Adapter ROM
000cc000-000cc1ff : Adapter ROM
000cc800-000d23ff : Adapter ROM
000f0000-000fffff : System ROM
00100000-cfeb1fff : System RAM
  00100000-00299ee9 : Kernel code
  00299eea-00335f43 : Kernel data
cfeb2000-cfec7fff : reserved
cfec8000-cfee7bff : ACPI Tables
cfee7c00-cfffffff : reserved
d0000000-d7ffffff : PCI Bus #0d
  d0000000-d7ffffff : 0000:0d:04.0
d8000000-ddffffff : PCI Bus #01
  da000000-ddffffff : PCI Bus #02
    da000000-dbffffff : PCI Bus #05
      da000000-dbffffff : PCI Bus #06
        da000000-dbffffff : 0000:06:00.0
          da000000-dbffffff : bnx2
    dc000000-ddffffff : PCI Bus #03
      dc000000-ddffffff : PCI Bus #04
        dc000000-ddffffff : 0000:04:00.0
          dc000000-ddffffff : bnx2
de0ff800-de0ffbff : 0000:00:1d.7
  de0ff800-de0ffbff : ehci_hcd
de100000-de2fffff : PCI Bus #08
  de100000-de1fffff : 0000:08:00.0
  de2ec000-de2effff : 0000:08:00.0
  de2f0000-de2fffff : 0000:08:00.0
de300000-de3fffff : PCI Bus #09
  de300000-de33ffff : 0000:09:00.0
  de3f8000-de3fbfff : 0000:09:00.0
    de3f8000-de3fbfff : qla2xxx
  de3fc000-de3fffff : 0000:09:00.1
    de3fc000-de3fffff : qla2xxx
de400000-de4fffff : PCI Bus #0d
  de400000-de41ffff : 0000:0d:04.0
  de4f0000-de4fffff : 0000:0d:04.0
de500000-de5fffff : PCI Bus #09
  de500000-de53ffff : 0000:09:00.1
e0000000-efffffff : reserved
fe000000-ffffffff : reserved
100000000-22fffffff : System RAM



Problem Description:

Depending on the kernel version writes are fast or slow on every kernel above 2.6.22 We have tested various driver versions, used utilities for firmware, but still slow writes on latest kernels. We compiled and tested more than 20 kernels
We just discovered that after a quick test on new dell hardware poweredge m600.

Most of the current distrib are on 2.6.18, except Ubuntu and various vserver or openvz kernels for debian. We tested redhat and suse too.




Steps to reproduce:

Very easy: We also check for an untar of the kernel (5x slower)
debian-test:~# dd if=/dev/zero of=/root/test.cdrom bs=10k count=60000
60000+0 enregistrements lus
60000+0 enregistrements écrits
614400000 octets (614 MB) copiés, 1,17602 seconde, 522 MB/s
debian-test:~# uname -a
Linux debian-test.pr.univmed.fr 2.6.19.7 #1 SMP Fri May 30 15:55:50 CEST 2008 i686 GNU/Linux

debian:~# dd if=/dev/zero of=test.cdrom  bs=10k count=60000
60000+0 records in
60000+0 records out
614400000 bytes (614 MB) copied, 7.51225 seconds, 81.8 MB/s
debian:~# uname -a
Linux debian 2.6.22-4-vserver-686 #1 SMP Tue Feb 12 22:02:04 UTC 2008 i686 GNU/Linux
Comment 1 Anonymous Emailer 2008-06-02 08:11:46 UTC 
Reply-To: James.Bottomley@HansenPartnership.com

On Mon, 2008-06-02 at 07:57 -0700, bugme-daemon@bugzilla.kernel.org
wrote:
> Very easy: We also check for an untar of the kernel (5x slower)
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom bs=10k count=60000
> 60000+0 enregistrements lus
> 60000+0 enregistrements écrits
> 614400000 octets (614 MB) copiés, 1,17602 seconde, 522 MB/s
> debian-test:~# uname -a
> Linux debian-test.pr.univmed.fr 2.6.19.7 #1 SMP Fri May 30 15:55:50
> CEST 2008
> i686 GNU/Linux
> 
> debian:~# dd if=/dev/zero of=test.cdrom  bs=10k count=60000
> 60000+0 records in
> 60000+0 records out
> 614400000 bytes (614 MB) copied, 7.51225 seconds, 81.8 MB/s
> debian:~# uname -a
> Linux debian 2.6.22-4-vserver-686 #1 SMP Tue Feb 12 22:02:04 UTC 2008
> i686
> GNU/Linux

What exactly is test.cdrom on?  A single disk?  If so, then your first
result is definitely bogus.  The maximum bandwidth of a single SAS link
is 300 MB/s, so it looks like the kernel is either caching the write or
has timing issues.  For a direct to platter speed, the data sheet for
your drive gives 55-89MB/s, so I'd say 81.8 is well within the range.

James
Comment 2 Roland Kletzing 2008-06-02 14:09:28 UTC 
i also don`t see an issue here.

the first write may fit to ram completely and thus getting cached, and the second looks like disk-speed.

does that go to the same path ?

try count=600000 or 6000000 instead of 60000 as data size for i/o tests should be >>ramsize.
Comment 3 Dominique LALOT 2008-06-03 00:00:49 UTC 
James and Roland

Sure there's write cache enabled and your remark make sense. That's the first thing I noticed when changing kernel.
We went from 2.8.18
SCSI device sda: drive cache: write through
SCSI device sda: 285155328 512-byte hdwr sectors (146000 MB)

testing with kernels 2.6.22 or 2.6.24, we noticed a change about the write cache, just changing the kernel on the same hardware.
[  115.986031] sd 4:1:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[  115.986494] sd 4:1:0:0: [sdb] 285155328 512-byte hardware sectors (146000 MB)

So we got a utility lsiutil to change the settings in the firmware about write cache, and we saw then write cache: enabled, but the speed stayed slow.
We also took a driver from lsi

About your remarks, I tested again using dd with a larger file (when untaring the kernel there's also a difference but it is less basic than dd)
The way dd reports its speed  may be not very accurate I agree, but it does not change from a kernel point of view.

Linux debian-test.pr.univmed.fr 2.6.21.7
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
100000+0 enregistrements lus
100000+0 enregistrements écrits
1024000000 octets (1,0 GB) copiés, 5,39271 seconde, 190 MB/s
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
100000+0 enregistrements lus
100000+0 enregistrements écrits
1024000000 octets (1,0 GB) copiés, 5,45364 seconde, 188 MB/s
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
200000+0 enregistrements lus
200000+0 enregistrements écrits
2048000000 octets (2,0 GB) copiés, 23,0492 seconde, 88,9 MB/s
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
200000+0 enregistrements lus
200000+0 enregistrements écrits
2048000000 octets (2,0 GB) copiés, 22,5306 seconde, 90,9 MB/s

I reboot and change kernel:
debian-test:~# uname -a
Linux debian-test.pr.univmed.fr 2.6.22.19 #1 SMP Fri May 30 19:53:56 CEST 2008 i686 GNU/Linux
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
100000+0 enregistrements lus
100000+0 enregistrements écrits
1024000000 octets (1,0 GB) copiés, 13,9614 seconde, 73,3 MB/s
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
100000+0 enregistrements lus
100000+0 enregistrements écrits
1024000000 octets (1,0 GB) copiés, 13,9406 seconde, 73,5 MB/s
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
200000+0 enregistrements lus
200000+0 enregistrements écrits
2048000000 octets (2,0 GB) copiés, 29,3472 seconde, 69,8 MB/s
debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
200000+0 enregistrements lus
200000+0 enregistrements écrits
2048000000 octets (2,0 GB) copiés, 29,1689 seconde, 70,2 MB/s
debian-test:~#

(I believe that, if I take a bigger file, we will get the same speed, the difference is due to the first data going to write cache)

What can we see:
1. having a larger file make the write cache less efficient (normal)
2. It seems that the write caching is no more working from 2.6.22 on our hardware (new blade servers from Dell m600). Even using firmware utilities didn't improve the speed. LSI firmware does not activate write cache and their BIOS has no setup for that. Switching from 2.6.18 to 2.6.22 makes the kernel  no more doing write cache. Changing in the firmware activate something.. just in dmesg, we see it: enabled again, but in fact there's no speed difference.

My subject should have  been: no more write caching
Comment 4 Anonymous Emailer 2008-06-03 07:12:12 UTC 
Reply-To: James.Bottomley@HansenPartnership.com

On Tue, 2008-06-03 at 00:00 -0700, bugme-daemon@bugzilla.kernel.org 
> Sure there's write cache enabled and your remark make sense. That's the first
> thing I noticed when changing kernel.
> We went from 2.8.18
> SCSI device sda: drive cache: write through
> SCSI device sda: 285155328 512-byte hdwr sectors (146000 MB)
> 
> testing with kernels 2.6.22 or 2.6.24, we noticed a change about the write
> cache, just changing the kernel on the same hardware.
> [  115.986031] sd 4:1:0:0: [sdb] Write cache: disabled, read cache: enabled,
> doesn't support DPO or FUA
> [  115.986494] sd 4:1:0:0: [sdb] 285155328 512-byte hardware sectors (146000
> MB)

The cache lines are actually saying the same thing, just in a different
way.  Write through means write cache disabled, read cache enabled (i.e.
writes have to be acknowledged only when they're on the platter not in
the cache).  The text of the cache identification was changed because
the term 'write through' was though to be unclear.

> So we got a utility lsiutil to change the settings in the firmware about
> write
> cache, and we saw then write cache: enabled, but the speed stayed slow.
> We also took a driver from lsi
> 
> About your remarks, I tested again using dd with a larger file (when untaring
> the kernel there's also a difference but it is less basic than dd)
> The way dd reports its speed  may be not very accurate I agree, but it does
> not
> change from a kernel point of view.
> 
> Linux debian-test.pr.univmed.fr 2.6.21.7
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
> 100000+0 enregistrements lus
> 100000+0 enregistrements écrits
> 1024000000 octets (1,0 GB) copiés, 5,39271 seconde, 190 MB/s
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
> 100000+0 enregistrements lus
> 100000+0 enregistrements écrits
> 1024000000 octets (1,0 GB) copiés, 5,45364 seconde, 188 MB/s
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
> 200000+0 enregistrements lus
> 200000+0 enregistrements écrits
> 2048000000 octets (2,0 GB) copiés, 23,0492 seconde, 88,9 MB/s
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
> 200000+0 enregistrements lus
> 200000+0 enregistrements écrits
> 2048000000 octets (2,0 GB) copiés, 22,5306 seconde, 90,9 MB/s

That's basically showing the OS effect of streaming writes caches, I
think.  You probably see the cache part of top rising rapidly.  Once you
overpower the OS cache, you'll eventually get the platter speed.

> I reboot and change kernel:
> debian-test:~# uname -a
> Linux debian-test.pr.univmed.fr 2.6.22.19 #1 SMP Fri May 30 19:53:56 CEST
> 2008
> i686 GNU/Linux
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
> 100000+0 enregistrements lus
> 100000+0 enregistrements écrits
> 1024000000 octets (1,0 GB) copiés, 13,9614 seconde, 73,3 MB/s
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=100000
> 100000+0 enregistrements lus
> 100000+0 enregistrements écrits
> 1024000000 octets (1,0 GB) copiés, 13,9406 seconde, 73,5 MB/s
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
> 200000+0 enregistrements lus
> 200000+0 enregistrements écrits
> 2048000000 octets (2,0 GB) copiés, 29,3472 seconde, 69,8 MB/s
> debian-test:~# dd if=/dev/zero of=/root/test.cdrom  bs=10k count=200000
> 200000+0 enregistrements lus
> 200000+0 enregistrements écrits
> 2048000000 octets (2,0 GB) copiés, 29,1689 seconde, 70,2 MB/s
> debian-test:~#

Within error bars, those are all really the same.  What it looks to me
like is that the mm layer is better at managing streaming writes.

> (I believe that, if I take a bigger file, we will get the same speed, the
> difference is due to the first data going to write cache)
> 
> What can we see:
> 1. having a larger file make the write cache less efficient (normal)
> 2. It seems that the write caching is no more working from 2.6.22 on our
> hardware (new blade servers from Dell m600). Even using firmware utilities
> didn't improve the speed. LSI firmware does not activate write cache and
> their
> BIOS has no setup for that. Switching from 2.6.18 to 2.6.22 makes the kernel 
> no more doing write cache. Changing in the firmware activate something.. just
> in dmesg, we see it: enabled again, but in fact there's no speed difference.
> 
> My subject should have  been: no more write caching

Not really ... your disk has a 16MB on disk cache ... that's not the
cause of the differences; it's the way the OS is caching data ... to see
the effect you're seeing, you need gigabytes of cache.  An OSs job is to
allocate spare memory for cache efficiently, and caching streaming
transactions is a complete waste of time (and further it's dangerous
because you get a huge data build up it can take minutes to clear, and
thus get lost on a crash), so it looks like 2.6.22 and beyond just got
better at recognising streaming transactions.

James
Comment 5 Dominique LALOT 2008-06-03 09:09:02 UTC 
James,

Should we consider, that such a difference is normal. You suggest that before the kernel was dangerous at writing data?
So unpacking linux kernel (for example) is 5x times slower and it is not a problem. That's just new way of caching data? We seldom see crashes (thanks to linux) and we have power supply.

I'd like testing on same hardware windows to see its behaviour and speed. Anyway thanks for the clarifying of cache: write through. As you say, it was not evident. 

So, now, what can we do to keep 2.6.21 behaviour? That's for a mail system writing lots of little files and performance matters too.

Dom
Comment 6 Roland Kletzing 2008-06-03 12:21:37 UTC 
>So unpacking linux kernel (for example) is 5x times slower

is it really ?

does 

time tar xzvf linux-kernel.tgz ;time sync

show a noticeable difference for for 2.6.21 and for 2.6.22+ ?
Comment 7 Anonymous Emailer 2008-06-03 13:15:34 UTC 
Reply-To: James.Bottomley@HansenPartnership.com

On Tue, 2008-06-03 at 09:09 -0700, bugme-daemon@bugzilla.kernel.org
wrote: 
> Should we consider, that such a difference is normal. You suggest that before
> the kernel was dangerous at writing data?

It's caching too much streaming data, yes.  The danger is largely the
amount of data you lose on a crash and mismanagement of the cache
starving other applications. It's not that much of a problem.  At an
estimated write speed of ~70MB/s your 1GB of data is only around 15s to
effect a full writeout.

> So unpacking linux kernel (for example) is 5x times slower and it is not a
> problem. That's just new way of caching data? We seldom see crashes (thanks
> to
> linux) and we have power supply.

There are many factors that could account for that.

> I'd like testing on same hardware windows to see its behaviour and speed.
> Anyway thanks for the clarifying of cache: write through. As you say, it was
> not evident. 
> 
> So, now, what can we do to keep 2.6.21 behaviour? That's for a mail system
> writing lots of little files and performance matters too.

Well, initially, I'd try a benchmark that simulates the actual problem,
like postmark.  A streaming write tells you very little about the entire
system performance under a mail server type load.

James
Comment 8 Dominique LALOT 2008-06-04 08:22:41 UTC 
Well,

I don't know what to say as a conclusion. We checked on another machine (sata devices). We confirmed the difference between the kernels.
I don't know the algorythum about the write caching, in fact we have seen a difference. If we stay under 80Mo, we stay in cache without effect from the write back or write through written in dmesg. 2.6.21 and above are OK.
It you test for 600Mo, you get hardware speed on 2.6.22+

As a conclusion: I was not lucky in doing such a test on a new hardware. I believed it comes from SAS and finaly that's more a change in Memory Management. By the way, if somebody can tell me where we can tune the max memory cache in kernel, that would be great. Anyway, for our purpose, it's not usefull.

Thanks

Dominique

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