Messages in this thread Patch in this message | | | From | Prarit Bhargava <> | Subject | [PATCH 2/3 v4] powercap, intel_rapl, implement check for minimum time window | Date | Wed, 16 Mar 2016 08:00:24 -0400 |
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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 feb063d..cf89b3d 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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