Bug 197923
Summary: | ZEN CPUs hang when power management enabled, workaround included. | ||
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Product: | Drivers | Reporter: | Mathieu Belanger (b747xx) |
Component: | Other | Assignee: | drivers_other |
Status: | NEW --- | ||
Severity: | blocking | CC: | chewi, kmueller, paulmck |
Priority: | P1 | ||
Hardware: | x86-64 | ||
OS: | Linux | ||
Kernel Version: | 4.13+ | Subsystem: | |
Regression: | No | Bisected commit-id: |
Description
Mathieu Belanger
2017-11-19 17:04:43 UTC
Please get your facts straight. Debian, Ubuntu, and Mageia have never enabled either option. OpenSUSE 42.3 (kernel 4.4) enables CONFIG_RCU_NOCB_CPU but not CONFIG_RCU_NOCB_CPU_ALL. Fedora enabled both since 3.16. RHEL enabled it earlier. It's probably still enabled in RHEL. https://bugzilla.redhat.com/show_bug.cgi?id=1109113 I build my own kernel anyway and I think reintroducing workarounds will reduce the incentive to fix it properly so I'm not calling for this, though I'm not against it either. Please see the original bug #196683. I've been facing those system hangs, too, until I switched on "daily computing" optimization in bios (ASUS PRIME X370-PRO BIOS 0902 09/08/2017) running 4.13.x. Switching to "daily computing" increases CPU speed to max MHz 3600 (instead of 3400) using Ryzen 7 1700X. Maybe it changes some more things I don't know off. But C states are definitely enabled: # zenstates.py -l P0 - Enabled - FID = 90 - DID = 8 - VID = 20 - Ratio = 36.00 - vCore = 1.35000 P1 - Enabled - FID = 90 - DID = 8 - VID = 20 - Ratio = 36.00 - vCore = 1.35000 P2 - Enabled - FID = 84 - DID = C - VID = 68 - Ratio = 22.00 - vCore = 0.90000 P3 - Disabled P4 - Disabled P5 - Disabled P6 - Disabled P7 - Disabled C6 State - Package - Enabled C6 State - Core - Enabled Klaus Mueller : It might by stabilisation by overclocking. It might help in some case but it also produce more heat. Your two higher P-States are set at 1.35V. My current Ryzen 1700 system, the vcore is set to 1.33V and the clock, 4.025Ghz. To confirm you actually have the same level of powersaving (C6), you can use "watch sensors" and wait on idle, the Vcore should go down to about 0.4V if it's actually working. (In reply to Mathieu Belanger from comment #3) Yes, lowest value was 0.39V during about 1 minute (max was 0.91). The machine runs 4 VMs in parallel. C-states are definitely working, because there is no difference in power consumption between 3600 and 3400 MHz (measured at the 230V power socket). Disabling C-states increases power consumption by about 9W. |