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From: Jens Axboe <axboe@fb.com>
To: Omar Sandoval <osandov@osandov.com>, <linux-block@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <kernel-team@fb.com>,
	Alexei Starovoitov <ast@fb.com>
Subject: Re: [PATCH] sbitmap: don't update the allocation hint on clear after resize
Date: Sat, 17 Sep 2016 13:39:59 -0600	[thread overview]
Message-ID: <227b6d24-8500-4ec9-5999-fd83f7221b8a@fb.com> (raw)
In-Reply-To: <29fb3ca2c78084b3548fd87c0c9a946e2b68bffc.1474139647.git.osandov@fb.com>

On 09/17/2016 01:20 PM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>
> 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>
> ---
> 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


  reply	other threads:[~2016-09-17 19:40 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-17  8:28 [PATCH v4 0/6] blk-mq: generalization and bug fixes for tag allocation Omar Sandoval
2016-09-17  8:28 ` [PATCH v4 1/6] blk-mq: abstract tag allocation out into sbitmap library Omar Sandoval
2016-09-17  8:28 ` [PATCH v4 2/6] sbitmap: allocate wait queues on a specific node Omar Sandoval
2016-09-17  8:28 ` [PATCH v4 3/6] sbitmap: push per-cpu last_tag into sbitmap_queue Omar Sandoval
2016-09-17  8:28 ` [PATCH v4 4/6] sbitmap: push alloc policy " Omar Sandoval
2016-09-17  8:28 ` [PATCH v4 5/6] sbitmap: randomize initial alloc_hint values Omar Sandoval
2016-09-17  8:28 ` [PATCH v4 6/6] sbitmap: re-initialize allocation hints after resize Omar Sandoval
2016-09-17 14:42 ` [PATCH v4 0/6] blk-mq: generalization and bug fixes for tag allocation Jens Axboe
2016-09-17 14:42   ` Jens Axboe
2016-09-17 19:20   ` [PATCH] sbitmap: don't update the allocation hint on clear after resize Omar Sandoval
2016-09-17 19:39     ` Jens Axboe [this message]
2016-09-17 19:49       ` Omar Sandoval

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