[PATCH 3/4] sched/fair: Add cfs bandwidth burst statistics

[Huaixin Chang]

Introduce statistics exports for the burstable cfs bandwidth
controller.

The following exports are included:

current_bw: current runtime in global pool
nr_burst:   number of periods bandwidth burst occurs
burst_time: cumulative wall-time that any cpus has
            used above quota in respective periods

Signed-off-by: Huaixin Chang <changhuai...@linux.alibaba.com>
Signed-off-by: Shanpei Chen <shanp...@linux.alibaba.com>
---
 kernel/sched/core.c  |  6 ++++++
 kernel/sched/fair.c  | 12 +++++++++++-
 kernel/sched/sched.h |  3 +++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9f1b05ad0411..d253903dbb4e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8681,6 +8681,8 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, 
u64 period, u64 quota,
                cfs_b->runtime = min(max_cfs_runtime, cfs_b->runtime);
        }
 
+       cfs_b->previous_runtime = cfs_b->runtime;
+
        /* Restart the period timer (if active) to handle new period expiry: */
        if (runtime_enabled)
                start_cfs_bandwidth(cfs_b, 1);
@@ -8929,6 +8931,10 @@ static int cpu_cfs_stat_show(struct seq_file *sf, void 
*v)
                seq_printf(sf, "wait_sum %llu\n", ws);
        }
 
+       seq_printf(sf, "current_bw %llu\n", cfs_b->runtime);
+       seq_printf(sf, "nr_burst %d\n", cfs_b->nr_burst);
+       seq_printf(sf, "burst_time %llu\n", cfs_b->burst_time);
+
        return 0;
 }
 #endif /* CONFIG_CFS_BANDWIDTH */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6a7c261d206a..4cd3dc16659c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4612,7 +4612,7 @@ static inline u64 sched_cfs_bandwidth_slice(void)
 static void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b,
                u64 overrun)
 {
-       u64 refill;
+       u64 refill, runtime;
 
        if (cfs_b->quota != RUNTIME_INF) {
 
@@ -4621,10 +4621,20 @@ static void __refill_cfs_bandwidth_runtime(struct 
cfs_bandwidth *cfs_b,
                        return;
                }
 
+               if (cfs_b->previous_runtime > cfs_b->runtime) {
+                       runtime = cfs_b->previous_runtime - cfs_b->runtime;
+                       if (runtime > cfs_b->quota) {
+                               cfs_b->burst_time += runtime - cfs_b->quota;
+                               cfs_b->nr_burst++;
+                       }
+               }
+
                overrun = min(overrun, cfs_b->max_overrun);
                refill = cfs_b->quota * overrun;
                cfs_b->runtime += refill;
                cfs_b->runtime = min(cfs_b->runtime, cfs_b->buffer);
+
+               cfs_b->previous_runtime = cfs_b->runtime;
        }
 }
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4f53ea8e92ce..04b0a1ce4c89 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -360,6 +360,7 @@ struct cfs_bandwidth {
        u64                     burst;
        u64                     buffer;
        u64                     max_overrun;
+       u64                     previous_runtime;
        s64                     hierarchical_quota;
 
        u8                      idle;
@@ -372,7 +373,9 @@ struct cfs_bandwidth {
        /* Statistics: */
        int                     nr_periods;
        int                     nr_throttled;
+       int                     nr_burst;
        u64                     throttled_time;
+       u64                     burst_time;
 #endif
 };
 
-- 
2.14.4.44.g2045bb6