Bug 11635
Summary: | strange message in dmesg for IDE HDD: cannot use LBA48 DMA - PIO mode will be used for accessing sectors > 268435456 | ||
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Product: | IO/Storage | Reporter: | Enrique (enrique_pinos) |
Component: | IDE | Assignee: | io_ide (io_ide) |
Status: | REJECTED WILL_NOT_FIX | ||
Severity: | normal | ||
Priority: | P1 | ||
Hardware: | All | ||
OS: | Linux | ||
Kernel Version: | 2.6.26.1 | Subsystem: | |
Regression: | --- | Bisected commit-id: |
Description
Enrique
2008-09-24 02:20:25 UTC
(In reply to comment #0) > hdc: cannot use LBA48 DMA - PIO mode will be used for accessing sectors > > 268435456 The IDE core honestly warns you that the controller doesn't support DMA for accesses abobe 137 GB. Where's the problem? > hdc: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63 > hdparm output: > hdparm -Tt /dev/hdc output: > /dev/hdc: > Timing cached reads: 388 MB in 2.01 seconds = 193.07 MB/sec > Timing buffered disk reads: 142 MB in 3.03 seconds = 46.89 MB/sec > (I want to get something above 500MB/sec) 500 MB/s on disk reads?! That's totally wrong expectaion. What I am seeing seems quite adequate speed for UltraDMA. And cached reads don't measure disk transfer speed but rather your CPU bus/memory bandwidth. > May it help (googled) > i found that related info: > https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/119730 > http://osdir.com/ml/ide/2005-03/msg00064.html The latter reports DMA timeouts -- now that's an error indeed. But the report is against 2.6.11. :-) I suggest this to be resolved INVALID. This is a hardware limit. > 500 MB/s on disk reads?! That's totally wrong expectaion
For my personal computer (Pentium IV)
hdparm -Tt /dev/hda
/dev/hda:
Timing cached reads: 1500 MB in 2.00 seconds = 749.31 MB/sec
Timing buffered disk reads: 184 MB in 3.01 seconds = 61.14 MB/sec
Server I'm using its athlon 1800MHz and I got same performance as previous server I got (k6-II @ 450MHz) I found server slow in transfers and high CPU usage (and k6-II never warnning me for hardware limits :S) This is the reason I'm in doubt.
Upgrading server didn't increase transfers between my PC and my server, in my local network :(
Thanks for replies.
> Timing buffered disk reads: 184 MB in 3.01 seconds = 61.14 MB/sec
is the disk speed
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