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[PATCH 0/3] powercap, intel_rapl, implement time window checks [v3]

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  [PATCH 0/3] powercap, intel_rapl, implement time window checks [v3] Prarit Bhargava <prarit@redhat.com> - 2016-01-25 01:50 +0100
    [PATCH 2/3] powercap, intel_rapl, implement check for minimum time window Prarit Bhargava <prarit@redhat.com> - 2016-01-25 01:50 +0100
    [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window Prarit Bhargava <prarit@redhat.com> - 2016-01-25 01:50 +0100

#1316145 — [PATCH 0/3] powercap, intel_rapl, implement time window checks [v3]

The Intel ASDM provides a maximum time window that can be specified when
setting a time window in the RAPL driver.  While the ASDM doesn't explicitly
provide a minimum time window value, it does provide a minimum time window
unit that also can be used as a minimum value.

This patchset implements barrier checking for the time windows, and adds
reporting of a known bug in which the maxmimum time window value may be
erroneously set to 0, as well as a module parameter to avoid the maximum
window checks on broken BIOSes.

[v3]: update 3/3 with minor changes

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>

Prarit Bhargava (3):
  powercap, intel_rapl, implement get_max_time_window
  powercap, intel_rapl, implement check for minimum time window
  powercap, intel_rapl, Add ignore_max_time_window_check module
    parameter for broken BIOSes

 drivers/powercap/intel_rapl.c   |   50 +++++++++++++++++++++++++++++++++++++++
 drivers/powercap/powercap_sys.c |    6 +++--
 2 files changed, 54 insertions(+), 2 deletions(-)

-- 
1.7.9.3

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#1316146 — [PATCH 2/3] powercap, intel_rapl, implement check for minimum time window

Using an small value for the time window results in a
bogus value for the time window.  For example,

[root@intel-chiefriver-03 linux]# echo 950 >
/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:1:4501502475370496

The Intel ASDM doesn't explicitly define a minimum time window.
The MSR_RAPL_POWER_UNIT register, read during initialization, does
specify a minimum time window unit so that can be used as a lower
bound for error checking.

After this change the minimum time window is properly clamped:

[root@intel-chiefriver-03 linux]# echo 950 >
/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 |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
index f765b2c..14753e5 100644
--- a/drivers/powercap/intel_rapl.c
+++ b/drivers/powercap/intel_rapl.c
@@ -516,6 +516,7 @@ static int set_time_window(struct powercap_zone *power_zone, int id,
 								u64 window)
 {
 	struct rapl_domain *rd;
+	struct rapl_package *rp;
 	int ret = 0;
 	u64 max_window;
 
@@ -524,12 +525,18 @@ static int set_time_window(struct powercap_zone *power_zone, int id,
 	if (ret < 0)
 		goto out;
 
-	if (window > max_window) {
+	rd = power_zone_to_rapl_domain(power_zone);
+	rp = find_package_by_id(rd->package_id);
+	/*
+	 * The Intel ASDM doesn't explicitly define a minimum time window.
+	 * The MSR_RAPL_POWER_UNIT register, read during initialization,
+	 * does contain the smallest unit of time that can be measured.
+	 */
+	if ((window > max_window) || (window < rp->time_unit)) {
 		ret = -EINVAL;
 		goto out;
 	}
 
-	rd = power_zone_to_rapl_domain(power_zone);
 	switch (rd->rpl[id].prim_id) {
 	case PL1_ENABLE:
 		rapl_write_data_raw(rd, TIME_WINDOW1, window);
-- 
1.7.9.3

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#1316147 — [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window

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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