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[PATCH 1/3] powercap, intel_rapl, implement get_max_time_window

Started byPrarit Bhargava <prarit@redhat.com>
First post2015-12-15 14:10 +0100
Last post2015-12-17 13:30 +0100
Articles 3 — 2 participants

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  [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window Prarit Bhargava <prarit@redhat.com> - 2015-12-15 14:10 +0100
    Re: [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window Seiichi Ikarashi <s.ikarashi@jp.fujitsu.com> - 2015-12-17 07:00 +0100
      Re: [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window Prarit Bhargava <prarit@redhat.com> - 2015-12-17 13:30 +0100

#1292151 — [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window

FromPrarit Bhargava <prarit@redhat.com>
Date2015-12-15 14:10 +0100
Subject[PATCH 1/3] powercap, intel_rapl, implement get_max_time_window
Message-ID<qFXwD-4x8-45@gated-at.bofh.it>
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@intel-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@intel-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@intel.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Radivoje Jovanovic <radivoje.jovanovic@intel.com>
Cc: Seiichi Ikarashi <s.ikarashi@jp.fujitsu.com>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.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)
+{
+	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 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 84419af..7d77b83 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; \
-- 
1.7.9.3

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#1293639

FromSeiichi Ikarashi <s.ikarashi@jp.fujitsu.com>
Date2015-12-17 07:00 +0100
Message-ID<qGzLz-3Dv-7@gated-at.bofh.it>
In reply to#1292151
On 2015-12-15 22:02, 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.

I have been having a question here long time.
Maximum Time Window (bits 53:48) in MSR_PKG_POWER_INFO is only
6-bit length even though Time Window for Power Limit #1 (bits 23:17)
and Time Window for Power Limit #2 (bits 55:49) in MSR_PKG_POWER_LIMIT 
are both 7-bit length, not 6.

Do Intel guys have an answer for it?


The patch itself looks good to me.
Just minor comments below:

> 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,

The 2nd arg "id" is not necessary.

> +			       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))

rapl_read_data_raw() can return -EINVAL and -ENODEV other than -EIO.

> +		ret = -EIO;

Is it OK to limit ret to -EIO here?

> +	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 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 84419af..7d77b83 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; \

An opposite question to above.
Is it OK not to limit the return value to -EINVAL here?
Do you want this function to return -EIO or something?

>  	} \
>  	\
>  	return -ENODATA; \
> 

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#1293837

FromPrarit Bhargava <prarit@redhat.com>
Date2015-12-17 13:30 +0100
Message-ID<qGFR0-7NE-9@gated-at.bofh.it>
In reply to#1293639

On 12/17/2015 12:45 AM, Seiichi Ikarashi wrote:
> On 2015-12-15 22:02, 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.
> 
> I have been having a question here long time.
> Maximum Time Window (bits 53:48) in MSR_PKG_POWER_INFO is only
> 6-bit length even though Time Window for Power Limit #1 (bits 23:17)
> and Time Window for Power Limit #2 (bits 55:49) in MSR_PKG_POWER_LIMIT 
> are both 7-bit length, not 6.

While looking at the MSR settings I had exactly the same question!  I too would
like to know the answer.

> 
> Do Intel guys have an answer for it?
> 
> 
> The patch itself looks good to me.
> Just minor comments below:
> 
>> 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,
> 
> The 2nd arg "id" is not necessary.

I'll drop this in v2.

> 
>> +			       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))
> 
> rapl_read_data_raw() can return -EINVAL and -ENODEV other than -EIO.
> 
>> +		ret = -EIO;
> 
> Is it OK to limit ret to -EIO here?

AFAICT it seems like it.  The only error that can occur here (at least by the
time this code is executed) is that there is a range error.  -EIO seems appropriate.

> 
>> +	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 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 84419af..7d77b83 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; \
> 
> An opposite question to above.
> Is it OK not to limit the return value to -EINVAL here?
> Do you want this function to return -EIO or something?

In this case, no, because the define is used by other values.  I think that
would limit all erros in the set_* functions to be -EIO.

P.
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