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Commit 5c64a8df authored by Omar Sandoval's avatar Omar Sandoval Committed by Jens Axboe
Browse files

sbitmap: don't update the allocation hint on clear after resize 



If we have a bunch of high-numbered bits allocated and then we resize
the struct sbitmap_queue, when those bits get cleared, we'll update the
hint and then have to re-randomize it repeatedly. Avoid that by checking
that the cleared bit is still a valid hint. No measurable performance
difference in the common case.

Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 05fd095d

lib/sbitmap.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -321,7 +321,7 @@ void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, 
{

{

	sbitmap_clear_bit(&sbq->sb, nr);

	sbitmap_clear_bit(&sbq->sb, nr);

	sbq_wake_up(sbq);

	sbq_wake_up(sbq);

	if (likely(!sbq->round_robin))

	if (likely(!sbq->round_robin && nr < sbq->sb.depth))

		*per_cpu_ptr(sbq->alloc_hint, cpu) = nr;

		*per_cpu_ptr(sbq->alloc_hint, cpu) = nr;

}

}

EXPORT_SYMBOL_GPL(sbitmap_queue_clear);

EXPORT_SYMBOL_GPL(sbitmap_queue_clear);