lkml.org 
[lkml]   [2018]   [Jul]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH] tg: show the sum wait time of an task group
    From
    Date
    Although we can rely on cpuacct to present the cpu usage of task
    group, it is hard to tell how intense the competition is between
    these groups on cpu resources.

    Monitoring the wait time of each process or sched_debug could cost
    too much, and there is no good way to accurately represent the
    conflict with these info, we need the wait time on group dimension.

    Thus we introduced group's wait_sum represent the conflict between
    task groups, which is simply sum the wait time of group's cfs_rq.

    The 'cpu.stat' is modified to show the statistic, like:

    nr_periods 0
    nr_throttled 0
    throttled_time 0
    wait_sum 2035098795584

    Now we can monitor the changing on wait_sum to tell how suffering
    a task group is in the fight of cpu resources.

    For example:
    (wait_sum - last_wait_sum) * 100 / (nr_cpu * period_ns) == X%

    means the task group paid X percentage of period on waiting
    for the cpu.

    Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
    ---
    Since RFC:
    redesigned the way to acquire wait_sum

    kernel/sched/core.c | 8 ++++++++
    1 file changed, 8 insertions(+)

    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index 78d8fac..cbff06b 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -6781,6 +6781,8 @@ static int __cfs_schedulable(struct task_group
    *tg, u64 period, u64 quota)

    static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
    {
    + int i;
    + u64 wait_sum = 0;
    struct task_group *tg = css_tg(seq_css(sf));
    struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;

    @@ -6788,6 +6790,12 @@ static int cpu_cfs_stat_show(struct seq_file *sf,
    void *v)
    seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
    seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);

    + if (schedstat_enabled()) {
    + for_each_possible_cpu(i)
    + wait_sum += tg->se[i]->statistics.wait_sum;
    + seq_printf(sf, "wait_sum %llu\n", wait_sum);
    + }
    +
    return 0;
    }
    #endif /* CONFIG_CFS_BANDWIDTH */
    --
    1.8.3.1
    \
     
     \ /
      Last update: 2018-07-03 07:42    [W:4.426 / U:0.088 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site