linux-kernel - Re: [PATCH] sbitmap: don't update the allocation hint on clear after resize

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Message-ID: <227b6d24-8500-4ec9-5999-fd83f7221b8a@fb.com>
Date:   Sat, 17 Sep 2016 13:39:59 -0600
From:   Jens Axboe <axboe@...com>
To:     Omar Sandoval <osandov@...ndov.com>, <linux-block@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <kernel-team@...com>,
        Alexei Starovoitov <ast@...com>
Subject: 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 <osandov@...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@...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