Commit ab522e33 authored Aug 22, 2016 by Dietmar Eggemann Committed by Ingo Molnar Sep 30, 2016

sched/fair: Fix fixed point arithmetic width for shares and effective load



Since commit:

  2159197d ("sched/core: Enable increased load resolution on 64-bit kernels")

we now have two different fixed point units for load:

- 'shares' in calc_cfs_shares() has 20 bit fixed point unit on 64-bit
  kernels. Therefore use scale_load() on MIN_SHARES.

- 'wl' in effective_load() has 10 bit fixed point unit. Therefore use
  scale_load_down() on tg->shares which has 20 bit fixed point unit on
  64-bit kernels.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471874441-24701-1-git-send-email-dietmar.eggemann@arm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 8f37961c

kernel/sched/fair.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -5017,9 +5017,9 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
		* wl = S * s'_i; see (2)
		*/
		if (W > 0 && w < W)
		wl = (w * (long)tg->shares) / W;
		wl = (w * (long)scale_load_down(tg->shares)) / W;
		else
		wl = tg->shares;
		wl = scale_load_down(tg->shares);

		/*
		* Per the above, wl is the new se->load.weight value; since

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