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

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Date:	Fri, 22 Jan 2016 09:27:43 +0900
From:	Seiichi Ikarashi <s.ikarashi@...fujitsu.com>
To:	Prarit Bhargava <prarit@...hat.com>, <linux-kernel@...r.kernel.org>
CC:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Radivoje Jovanovic <radivoje.jovanovic@...el.com>,
	Mathias Krause <minipli@...glemail.com>,
	Ajay Thomas <ajay.thomas.david.rajamanickam@...el.com>
Subject: Re: [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window

On 2016-01-22 01:15, 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>
> ---
>  drivers/powercap/intel_rapl.c   |   31 +++++++++++++++++++++++++++++++
>  drivers/powercap/powercap_sys.c |    6 ++++--
>  2 files changed, 35 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index cc97f08..f765b2c 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -493,13 +493,42 @@ static int get_current_power_limit(struct powercap_zone *power_zone, int id,
>  	return ret;
>  }
>  
> +static int get_max_time_window(struct powercap_zone *power_zone, int id,
> +			       u64 *data)

The 2nd arg "id" is not necessary.

--
Seiichi