Red Hat Bugzilla – Bug 489566
when booted with P-state limit, limit can never be increased
Last modified: 2014-06-09 09:49:20 EDT
There is an upstream git commit that should fix this:
Certain modern servers contain BIOS functionality to set a P-State limit. This works by generating an ACPI_PROCESSOR_NOTIFY_PERFORMANCE event and re-reading the APCI _PPC object. _PPC indicates the smallest index (highest frequency) that the OS is allowed to select.
In general, this works fine under EL5.3. But if the cpufreq driver
(acpi-cpufreq) initializes while the _PPC object is already active (_PPC > 0),
the max frequency limit is set such that it can't be changed to normal when a
new ACPI_PROCESSOR_NOTIFY_PERFORMANCE event arrives and _PPC is set back to 0.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. reboot, or (rmmod acpi-cpufreq; modprobe acpi-cpufreq) while power
consumption is set to "minimum power".
2. change power setting to "max performance"
scaling_max_freq is still set to the frequency corresponding to "minimum power"
scaling_max_freq is set to maximum (=cpuinfo_max_freq)
Do we have one of these systems in RHTS?
Created attachment 336296 [details]
Brew build for test kernel packages with this bug and BZ494288 fixes are here:
To reproduce this bug is crucial to set "Minimum power" and "Apply" in iRMC webpage _after_ reboot console command. If we first change power settings and then reboot machine everything works just fine.
Patch pointed by Marc in Comment #1 fix the bug. I tested it on 10.33.8.173 machine (thanks Gary) and everything works.
Looks kernel I build for customer to test in Comment #12 just not contain the patch. My bad, I probably forgot to commit change to git repo before building the rpm.
If You want to give kernel to customer for confirmation here is brew build:
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
You can download this test kernel from http://people.redhat.com/dzickus/el5
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*** Bug 563344 has been marked as a duplicate of this bug. ***
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
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