sched: Remove needless round trip nsecs <-> tick conversion of steal time (300a9d88) · Commits · 戴 / test

When update_rq_clock_task() accounts the pending steal time for a task, it converts the steal delta from nsecs to tick then from tick to nsecs. There is no apparent good reason for doing that though because both the task clock and the prev steal delta are u64 and store values in nsecs. So lets remove the needless conversion. Cc: Ingo Molnar <mingo@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Acked-by:

Rik van Riel <riel@redhat.com> Signed-off-by:

Frederic Weisbecker <fweisbec@gmail.com>

kernel/sched/core.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -823,19 +823,13 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
		#endif
		#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
		if (static_key_false((&paravirt_steal_rq_enabled))) {
		u64 st;

		steal = paravirt_steal_clock(cpu_of(rq));
		steal -= rq->prev_steal_time_rq;

		if (unlikely(steal > delta))
		steal = delta;

		st = steal_ticks(steal);
		steal = st * TICK_NSEC;

		rq->prev_steal_time_rq += steal;

		delta -= steal;
		}
		#endif

kernel/sched/sched.h

+0 −10

Original line number	Diff line number	Diff line
		@@ -1214,16 +1214,6 @@ extern void update_idle_cpu_load(struct rq *this_rq);

		extern void init_task_runnable_average(struct task_struct *p);

		#ifdef CONFIG_PARAVIRT
		static inline u64 steal_ticks(u64 steal)
		{
		if (unlikely(steal > NSEC_PER_SEC))
		return div_u64(steal, TICK_NSEC);

		return __iter_div_u64_rem(steal, TICK_NSEC, &steal);
		}
		#endif

		static inline void inc_nr_running(struct rq *rq)
		{
		rq->nr_running++;

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