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Date: Thu, 31 Mar 2016 18:28:59 +0000
From: "Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"prarit@...hat.com" <prarit@...hat.com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
CC: "Jovanovic, Radivoje" <radivoje.jovanovic@...el.com>,
"s.ikarashi@...fujitsu.com" <s.ikarashi@...fujitsu.com>,
"David Rajamanickam, Ajay Thomas"
<ajay.thomas.david.rajamanickam@...el.com>,
"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
"minipli@...glemail.com" <minipli@...glemail.com>
Subject: Re: [PATCH 1/3 v4] powercap, intel_rapl, implement
get_max_time_window
On Mon, 2016-03-21 at 08:27 -0400, 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.
>
Usually this field has lot of junk. It is not supported uniformly.
The system provides this value from another ACPI element called PPCC.
If supported this will be in
$ /sys/bus/pci/devices/0000:00:04.0/power_limits
$ grep . *
power_limit_0_max_uw:15000000
power_limit_0_min_uw:125000
power_limit_0_step_uw:1000000
power_limit_0_tmax_us:32000000
power_limit_0_tmin_us:28000000
power_limit_1_max_uw:25000000
power_limit_1_min_uw:25000000
power_limit_1_step_uw:1000000
power_limit_1_tmax_us:0
power_limit_1_tmin_us:0
Thanks,
Srinivas
> 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 6c592dc..feb063d 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)
> +{
> + struct rapl_domain *rd;
> + int ret = 0;
> + u64 val;
> +
> + get_online_cpus();
> + rd = power_zone_to_rapl_domain(power_zone);
> +
> + if (rapl_read_data_raw(rd, MAX_TIME_WINDOW, true, &val))
> + ret = -EIO;
> + else
> + *data = val;
> +
> + put_online_cpus();
> + return ret;
> +}
> +
> static int set_time_window(struct powercap_zone *power_zone, int id,
> u64
> window)
> {
> struct rapl_domain *rd;
> int ret = 0;
> + u64 max_window;
>
> get_online_cpus();
> + ret = get_max_time_window(power_zone, id, &max_window);
> + if (ret < 0)
> + goto out;
> +
> + if (window > max_window) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> rd = power_zone_to_rapl_domain(power_zone);
> switch (rd->rpl[id].prim_id) {
> case PL1_ENABLE:
> @@ -511,6 +540,7 @@ static int set_time_window(struct powercap_zone
> *power_zone, int id,
> default:
> ret = -EINVAL;
> }
> +out:
> put_online_cpus();
> return ret;
> }
> @@ -590,6 +620,7 @@ static const struct powercap_zone_constraint_ops
> constraint_ops = {
> .set_time_window_us = set_time_window,
> .get_time_window_us = get_time_window,
> .get_max_power_uw = get_max_power,
> + .get_max_time_window_us = get_max_time_window,
> .get_name = get_constraint_name,
> };
>
> diff --git a/drivers/powercap/powercap_sys.c
> b/drivers/powercap/powercap_sys.c
> index 14bde0d..53fad0f 100644
> --- a/drivers/powercap/powercap_sys.c
> +++ b/drivers/powercap/powercap_sys.c
> @@ -101,7 +101,7 @@ static ssize_t store_constraint_##_attr(struct
> device *dev,\
> int err; \
> u64 value; \
> struct powercap_zone *power_zone = to_powercap_zone(dev); \
> - int id; \
> + int id, ret; \
> struct powercap_zone_constraint *pconst;\
> \
> if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
> @@ -113,8 +113,10 @@ static ssize_t store_constraint_##_attr(struct
> device *dev,\
> if (err) \
> return -EINVAL; \
> if (pconst && pconst->ops && pconst->ops->set_##_attr) { \
> - if (!pconst->ops->set_##_attr(power_zone, id,
> value)) \
> + ret = pconst->ops->set_##_attr(power_zone, id,
> value); \
> + if (!ret) \
> return count; \
> + return ret; \
> } \
> \
> return -ENODATA; \
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