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author | 2019-11-21 03:44:25 +0100 | |
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committer | 2019-11-21 07:33:23 +0100 | |
commit | 5a1c95580f1d89c8a736bb02ecd82a8858388b8a (patch) | |
tree | 90a120e1683e4e81829317127b1cecfa7c8ab637 /kernel/sched | |
parent | sched/cpufreq: Move the cfs_rq_util_change() call to cpufreq_update_util() (diff) | |
download | linux-5a1c95580f1d89c8a736bb02ecd82a8858388b8a.tar.gz linux-5a1c95580f1d89c8a736bb02ecd82a8858388b8a.tar.bz2 linux-5a1c95580f1d89c8a736bb02ecd82a8858388b8a.zip |
sched/cputime: Support other fields on kcpustat_field()
Provide support for user, nice, guest and guest_nice fields through
kcpustat_field().
Whether we account the delta to a nice or not nice field is decided on
top of the nice value snapshot taken at the time we call kcpustat_field().
If the nice value of the task has been changed since the last vtime
update, we may have inacurrate distribution of the nice VS unnice
cputime.
However this is considered as a minor issue compared to the proper fix
that would involve interrupting the target on nice updates, which is
undesired on nohz_full CPUs.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191121024430.19938-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/cputime.c | 54 |
1 files changed, 43 insertions, 11 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index e0cd20693ef5..27b5406222fc 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -912,11 +912,21 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime) } while (read_seqcount_retry(&vtime->seqcount, seq)); } +static u64 kcpustat_user_vtime(struct vtime *vtime) +{ + if (vtime->state == VTIME_USER) + return vtime->utime + vtime_delta(vtime); + else if (vtime->state == VTIME_GUEST) + return vtime->gtime + vtime_delta(vtime); + return 0; +} + static int kcpustat_field_vtime(u64 *cpustat, - struct vtime *vtime, + struct task_struct *tsk, enum cpu_usage_stat usage, int cpu, u64 *val) { + struct vtime *vtime = &tsk->vtime; unsigned int seq; int err; @@ -946,9 +956,37 @@ static int kcpustat_field_vtime(u64 *cpustat, *val = cpustat[usage]; - if (vtime->state == VTIME_SYS) - *val += vtime->stime + vtime_delta(vtime); - + /* + * Nice VS unnice cputime accounting may be inaccurate if + * the nice value has changed since the last vtime update. + * But proper fix would involve interrupting target on nice + * updates which is a no go on nohz_full (although the scheduler + * may still interrupt the target if rescheduling is needed...) + */ + switch (usage) { + case CPUTIME_SYSTEM: + if (vtime->state == VTIME_SYS) + *val += vtime->stime + vtime_delta(vtime); + break; + case CPUTIME_USER: + if (task_nice(tsk) <= 0) + *val += kcpustat_user_vtime(vtime); + break; + case CPUTIME_NICE: + if (task_nice(tsk) > 0) + *val += kcpustat_user_vtime(vtime); + break; + case CPUTIME_GUEST: + if (vtime->state == VTIME_GUEST && task_nice(tsk) <= 0) + *val += vtime->gtime + vtime_delta(vtime); + break; + case CPUTIME_GUEST_NICE: + if (vtime->state == VTIME_GUEST && task_nice(tsk) > 0) + *val += vtime->gtime + vtime_delta(vtime); + break; + default: + break; + } } while (read_seqcount_retry(&vtime->seqcount, seq)); return 0; @@ -965,15 +1003,10 @@ u64 kcpustat_field(struct kernel_cpustat *kcpustat, if (!vtime_accounting_enabled_cpu(cpu)) return cpustat[usage]; - /* Only support sys vtime for now */ - if (usage != CPUTIME_SYSTEM) - return cpustat[usage]; - rq = cpu_rq(cpu); for (;;) { struct task_struct *curr; - struct vtime *vtime; rcu_read_lock(); curr = rcu_dereference(rq->curr); @@ -982,8 +1015,7 @@ u64 kcpustat_field(struct kernel_cpustat *kcpustat, return cpustat[usage]; } - vtime = &curr->vtime; - err = kcpustat_field_vtime(cpustat, vtime, usage, cpu, &val); + err = kcpustat_field_vtime(cpustat, curr, usage, cpu, &val); rcu_read_unlock(); if (!err) |