linux-kernel - Re: [PATCH 1/3 v4] powercap, intel_rapl, implement get_max_time

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Date:	Sat, 19 Mar 2016 03:18:32 +0100
From:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
To:	Prarit Bhargava <prarit@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Radivoje Jovanovic <radivoje.jovanovic@...el.com>,
	Seiichi Ikarashi <s.ikarashi@...fujitsu.com>,
	Mathias Krause <minipli@...glemail.com>,
	Ajay Thomas <ajay.thomas.david.rajamanickam@...el.com>
Subject: Re: [PATCH 1/3 v4] powercap, intel_rapl, implement
 get_max_time_window

On 3/16/2016 1:00 PM, Prarit Bhargava wrote:
> The MSR_PKG_POWER_INFO register (Intel ASDM, section 14.9.3
> "Package RAPL Domain") provides a maximum time window which the
> system can support.  This window is read-only and is currently
> not examined when setting the time windows for the package.
>
> This patch implements get_max_time_window_us() and checks the window when
> a user attempts to set power capping for the package.
>
> Before the patch it was possible to set the window to, for example, 10000
> micro seconds:
>
> [root@...el-chiefriver-03 rhel7]# echo 10000 >
> /sys/devices/virtual/powercap/intel-rapl/intel-rapl\:0/constraint_0_time_window_us;
> egrep ^ /sys/devices/virtual/powercap/intel-rapl/intel-rapl\:0/constraint_0_time_window_us
>
> /sys/devices/virtual/powercap/intel-rapl/intel-rapl:0/constraint_0_time_window_us:1:9765
>
> but from 'turbostat -d', the package is limited to 976us:
>
> cpu0: MSR_PKG_POWER_INFO: 0x01200168 (45 W TDP, RAPL 36 - 0 W, 0.000977 sec.)
>
> (Note, there appears to be a rounding issue in turbostat which needs to
> also be fixed.  Looking at the values in the register it is clear the
> value is 1/1024 = 976us.)
>
> After the patch we are limited by the maximum time window:
>
> [root@...el-chiefriver-03 rhel7]# echo 10000 >
> /sys/devices/virtual/powercap/intel-rapl/intel-rapl\:0/constraint_0_time_window_us;
> egrep ^ /sys/devices/virtual/powercap/intel-rapl/intel-rapl\:0/constraint_0_time_window_us
>
> -bash: echo: write error: Invalid argument
> /sys/devices/virtual/powercap/intel-rapl/intel-rapl:0/constraint_0_time_window_us:1:976
>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> Cc: Prarit Bhargava <prarit@...hat.com>
> Cc: Radivoje Jovanovic <radivoje.jovanovic@...el.com>
> Cc: Seiichi Ikarashi <s.ikarashi@...fujitsu.com>
> Cc: Mathias Krause <minipli@...glemail.com>
> Cc: Ajay Thomas <ajay.thomas.david.rajamanickam@...el.com>
> Signed-off-by: Prarit Bhargava <prarit@...hat.com>

Can you please resend the patches with CCs to linux-pm@...r.kernel.org?

They are much easier to handle to me then.

Thanks,
Rafael