Re: [PATCH] sbitmap: don't update the allocation hint on clear after resize
On Sat, Sep 17, 2016 at 01:39:59PM -0600, Jens Axboe wrote: > On 09/17/2016 01:20 PM, Omar Sandoval wrote: > > From: Omar Sandoval > > > > 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 > > --- > > Jens, > > > > Small tweak to patch 6 that occurred to me after I sent the series out. > > Feel free to fold it in to patch 6 or apply it separately as you see > > fit. > > No worries. I can't fold since the series was already applied, so I just > added the extra patch. > Okay with me, thanks! -- Omar -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] sbitmap: don't update the allocation hint on clear after resize
On 09/17/2016 01:20 PM, Omar Sandoval wrote: From: Omar Sandoval 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 --- Jens, Small tweak to patch 6 that occurred to me after I sent the series out. Feel free to fold it in to patch 6 or apply it separately as you see fit. No worries. I can't fold since the series was already applied, so I just added the extra patch. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] sbitmap: don't update the allocation hint on clear after resize
From: Omar Sandoval
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
---
Jens,
Small tweak to patch 6 that occurred to me after I sent the series out.
Feel free to fold it in to patch 6 or apply it separately as you see
fit.
Thanks!
lib/sbitmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index f736c52..e408089 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -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);
--
2.9.3
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