linux-kernel - Re: [PATCH v8 0/6] cpufreq: powernv: Redesign the presentation of throttle notification and solve bug-fixes in the driver

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Date:	Wed, 03 Feb 2016 21:44:49 +0530
From:	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
CC:	linuxppc-dev@...abs.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	pc@...ibm.com, anton@...ba.org, ego@...ux.vnet.ibm.com,
	shreyas@...ux.vnet.ibm.com, bsingharora@...il.com,
	mpe@...erman.id.au
Subject: Re: [PATCH v8 0/6] cpufreq: powernv: Redesign the presentation of
 throttle notification and solve bug-fixes in the driver

Hi Rafael,

On 02/03/2016 07:10 PM, Rafael J. Wysocki wrote:
> Hi,
> 
> On Tue, Feb 2, 2016 at 8:41 PM, Shilpasri G Bhat
> <shilpa.bhat@...ux.vnet.ibm.com> wrote:
>> In POWER8, OCC(On-Chip-Controller) can throttle the frequency of the
>> CPU when the chip crosses its thermal and power limits. Currently,
>> powernv-cpufreq driver detects and reports this event as a console
>> message. Some machines may not sustain the max turbo frequency in all
>> conditions and can be throttled frequently. This can lead to the
>> flooding of console with throttle messages. So this patchset aims to
>> redesign the presentation of this event via sysfs counters and
>> tracepoints. And it also fixes couple of bugs reported in the driver.
>>
>> - Patch [1] fixes a memory leak bug
>> - Patch [2] fixes the cpu hot-plug bug in powernv_cpufreq_work_fn().
>> - Patch [3] solves a bug in powernv_cpufreq_throttle_check(), which
>>   calls in to cpu_to_chip_id() in hot path which reads DT every time
>>   to find the chip id.
>> - Patches [4] to [6] will add a perf trace point
>>   "power:powernv_throttle" and sysfs throttle counter stats in
>>   /sys/devices/system/cpu/cpufreq/chipN.
>>
>> Changes from v7:
>> - Changes in patch[6] involves adding a table to represent the
>>   throtle stats in frequency X reason layout. Detailed version log
>>   in the patch.
>>
>> Changes from v6:
>> - Changes wrt comments from Balbir Singh and Viresh Kumar. Details in
>>   the version log of the patches.
>>
>> Changes from v5:
>> - Fix kbuild error:
>> drivers/cpufreq/powernv-cpufreq.c:428:2: error: implicit declaration of
>> function 'get_online_cpus' [-Werror=implicit-function-declaration]
>>
>> Changes from v4:
>> - Fix a hot-plug bug in powernv_cpufreq_work_fn()
>> - Changes wrt Gautham's and Shreyas's comments
>>
>> Changes from v3:
>> - Add a fix to replace cpu_to_chip_id() with simpler PIR shift to
>>   obtain the chip id.
>> - Break patch2 in to two patches separating the tracepoint and sysfs
>>   attribute changes.
>>
>> Changes from v2:
>> - Fixed kbuild test warning.
>> drivers/cpufreq/powernv-cpufreq.c:609:2: warning: ignoring return
>> value of 'kstrtoint', declared with attribute warn_unused_result
>> [-Wunused-result]
>> Shilpasri G Bhat (6):
>>   cpufre: powernv: Free 'chips' on module exit
>>   cpufreq: powernv: Hot-plug safe the kworker thread
>>   cpufreq: powernv: Remove cpu_to_chip_id() from hot-path
>>   cpufreq: powernv/tracing: Add powernv_throttle tracepoint
>>   cpufreq: powernv: Replace pr_info with trace print for throttle event
>>   cpufreq: powernv: Add sysfs attributes to show throttle stats
> 
> It looks like patches [1-5/6] are not objectionable and I can apply
> them without the last one if you want me to.
> 

Yes please apply Patch[1-5]. Thanks.

Regards,
Shilpa