sched/cputime: Fix cpu_timer_sample_group() double accounting (23cfa361) · Commits · 戴 / test

While looking over the cpu-timer code I found that we appear to add the delta for the calling task twice, through: cpu_timer_sample_group() thread_group_cputimer() thread_group_cputime() times->sum_exec_runtime += task_sched_runtime(); *sample = cputime.sum_exec_runtime + task_delta_exec(); Which would make the sample run ahead, making the sleep short. Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20141112113737.GI10476@twins.programming.kicks-ass.net Signed-off-by:

Ingo Molnar <mingo@kernel.org>

include/linux/kernel_stat.h

+0 −5

Original line number	Diff line number	Diff line
		@@ -77,11 +77,6 @@ static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
		return kstat_cpu(cpu).irqs_sum;
		}

		/*
		* Lock/unlock the current runqueue - to extract task statistics:
		*/
		extern unsigned long long task_delta_exec(struct task_struct *);

		extern void account_user_time(struct task_struct *, cputime_t, cputime_t);
		extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t);
		extern void account_steal_time(cputime_t);

kernel/sched/core.c

+0 −13

Original line number	Diff line number	Diff line
		@@ -2499,19 +2499,6 @@ static u64 do_task_delta_exec(struct task_struct p, struct rq rq)
		return ns;
		}

		unsigned long long task_delta_exec(struct task_struct *p)
		{
		unsigned long flags;
		struct rq *rq;
		u64 ns = 0;

		rq = task_rq_lock(p, &flags);
		ns = do_task_delta_exec(p, rq);
		task_rq_unlock(rq, p, &flags);

		return ns;
		}

		/*
		* Return accounted runtime for the task.
		* In case the task is currently running, return the runtime plus current's

kernel/time/posix-cpu-timers.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -553,7 +553,7 @@ static int cpu_timer_sample_group(const clockid_t which_clock,
		*sample = cputime_to_expires(cputime.utime);
		break;
		case CPUCLOCK_SCHED:
		*sample = cputime.sum_exec_runtime + task_delta_exec(p);
		*sample = cputime.sum_exec_runtime;
		break;
		}
		return 0;

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