cgroup: cpu.stats reset counters support

PATCH NAK David Collins 2 participants 2 messages Feb 15, 2016 1 message not in the archive

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Scheduler cgroup

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David Collins

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2016-02-15 21:14 UTC #0 lore raw

PATCH 1/1 cgroup: cpu.stats reset counters support

This patch allows the cpu.stats values to be reset in cgroups without having to remove and recreate it. I wrote this patch because I've had use cases where resetting the counters made it much easier to read, and it may help with custom userland scripts when parsing statistics.

Many other components of cgroups allows stats to be reset, such as cpuacct.stats. To reset the stats counters, simply echo 0 > cpu.stats

kernel/sched/core.c 2016-02-15 13:48:14.439443599 -0600 renamed from kernel/sched/core.c.orig 2016-02-15 13:47:22.359443599 -0600 +17 -0

@@ -8629,6 +8629,22 @@ static int cpu_stats_show(struct seq_fil
 
     return 0;
 }
+
+static int cpu_stats_reset(struct cgroup_subsys_state *css, struct cftype *cft,
+                u64 reset)
+{
+    struct task_group *tg = css_tg(css);
+    struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+
+    raw_spin_lock(&cfs_b->lock);
+    cfs_b->nr_periods = 0;
+    cfs_b->nr_throttled = 0;
+    cfs_b->throttled_time = 0;
+    raw_spin_unlock(&cfs_b->lock);
+
+    return 0;
+}
+
 #endif /* CONFIG_CFS_BANDWIDTH */
 #endif /* CONFIG_FAIR_GROUP_SCHED */

@@ -8680,6 +8696,7 @@ static struct cftype cpu_files[] = {
     {
         .name = "stat",
         .seq_show = cpu_stats_show,
+        .write_u64 = cpu_stats_reset,
     },
 #endif
 #ifdef CONFIG_RT_GROUP_SCHED

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Tejun Heo

Nacked-by NAK

2016-02-15 21:15 UTC #2 lore raw

Quoted 3 lines · David Collins

This patch allows the cpu.stats values to be reset in cgroups without having to remove and recreate it. I wrote this patch because I've had use cases where resetting the counters made it much easier to read, and it may help with custom userland scripts when parsing statistics.
Many other components of cgroups allows stats to be reset, such as cpuacct.stats. To reset the stats counters, simply echo 0 > cpu.stats

Please don't do this. The right thing to do is to read accumluative values from userland and calculate the delta. Going forward, no other cgroup stat files are gonna support resetting.

Nacked-by Tejun Heo <[email protected]>

Thanks.

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tejun