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

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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: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Omar Sandoval 2016-09-17 12:20:54 -07:00 committed by Jens Axboe
parent 05fd095d53
commit 5c64a8df0c
1 changed files with 1 additions and 1 deletions
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2
lib/sbitmap.c
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@ -321,7 +321,7 @@ void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
{
sbitmap_clear_bit(&sbq->sb, nr);
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;
}
EXPORT_SYMBOL_GPL(sbitmap_queue_clear);