sched/fair: Add cfs bandwidth burst statistics

mainline inclusion
from mainline-v5.15-rc4
commit bcb1704a
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5CPWE
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bcb1704a1ed2de580a46f28922e223a65f16e0f5

--------------------------------

Two new statistics are introduced to show the internal of burst feature
and explain why burst helps or not.

nr_bursts:  number of periods bandwidth burst occurs
burst_time: cumulative wall-time (in nanoseconds) that any cpus has
	    used above quota in respective periods
Co-developed-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Signed-off-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Co-developed-by: NTianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: NTianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: NHuaixin Chang <changhuaixin@linux.alibaba.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NDaniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: NTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210830032215.16302-2-changhuaixin@linux.alibaba.comSigned-off-by: NHui Tang <tanghui20@huawei.com>
Reviewed-by: NChen Hui <judy.chenhui@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/sched/core.c

@@ -8517,6 +8517,9 @@ static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
 		seq_printf(sf, "wait_sum %llu\n", ws);
 	}
 
+	seq_printf(sf, "nr_bursts %d\n", cfs_b->nr_burst);
+	seq_printf(sf, "burst_time %llu\n", cfs_b->burst_time);
+
 	return 0;
 }
 #endif /* CONFIG_CFS_BANDWIDTH */
@@ -8683,16 +8686,20 @@ static int cpu_extra_stat_show(struct seq_file *sf,
 	{
 		struct task_group *tg = css_tg(css);
 		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
-		u64 throttled_usec;
+		u64 throttled_usec, burst_usec;
 
 		throttled_usec = cfs_b->throttled_time;
 		do_div(throttled_usec, NSEC_PER_USEC);
+		burst_usec = cfs_b->burst_time;
+		do_div(burst_usec, NSEC_PER_USEC);
 
 		seq_printf(sf, "nr_periods %d\n"
 			   "nr_throttled %d\n"
-			   "throttled_usec %llu\n",
+			   "throttled_usec %llu\n"
+			   "nr_bursts %d\n"
+			   "burst_usec %llu\n",
 			   cfs_b->nr_periods, cfs_b->nr_throttled,
-			   throttled_usec);
+			   throttled_usec, cfs_b->nr_burst, burst_usec);
 	}
 #endif
 	return 0;

kernel/sched/fair.c

@@ -4738,11 +4738,20 @@ static inline u64 sched_cfs_bandwidth_slice(void)
  */
 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
 {
+	s64 runtime;
+
 	if (unlikely(cfs_b->quota == RUNTIME_INF))
 		return;
 
 	cfs_b->runtime += cfs_b->quota;
+	runtime = cfs_b->runtime_snap - cfs_b->runtime;
+	if (runtime > 0) {
+		cfs_b->burst_time += runtime;
+		cfs_b->nr_burst++;
+	}
+
 	cfs_b->runtime = min(cfs_b->runtime, cfs_b->quota + cfs_b->burst);
+	cfs_b->runtime_snap = cfs_b->runtime;
 }
 
 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)

kernel/sched/sched.h

@@ -387,12 +387,15 @@ struct cfs_bandwidth {
 
 #if !defined(__GENKSYMS__)
 	u64			burst;
+	u64			runtime_snap;
+	int			nr_burst;
+	u64			burst_time;
 #else
 	KABI_RESERVE(1)
-#endif
 	KABI_RESERVE(2)
 	KABI_RESERVE(3)
 	KABI_RESERVE(4)
+#endif
 	KABI_RESERVE(5)
 	KABI_RESERVE(6)
 #endif