Commit db84a72a authored Sep 01, 2020 by Tejun Heo Committed by Jens Axboe Sep 01, 2020

blk-iocost: clamp inuse and skip noops in __propagate_weights()



__propagate_weights() currently expects the callers to clamp inuse within
[1, active], which is needlessly fragile. The inuse adjustment logic is
going to be revamped, in preparation, let's make __propagate_weights() clamp
inuse on entry.

Also, make it avoid weight updates altogether if neither active or inuse is
changed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 00410f1b

block/blk-iocost.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -897,7 +897,10 @@ static void __propagate_weights(struct ioc_gq *iocg, u32 active, u32 inuse)

		lockdep_assert_held(&ioc->lock);

		inuse = min(active, inuse);
		inuse = clamp_t(u32, inuse, 1, active);

		if (active == iocg->active && inuse == iocg->inuse)
		return;

		for (lvl = iocg->level - 1; lvl >= 0; lvl--) {
		struct ioc_gq *parent = iocg->ancestors[lvl];