linux-kernel - Re: [PATCH v2 1/4] sbitmap: optimise sbitmap_deferred

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Message-ID: <e71a58b5-1315-d655-4e1e-cd7529acfd6b@huawei.com>
Date:   Tue, 24 Nov 2020 14:11:51 +0000
From:   John Garry <john.garry@...wei.com>
To:     Pavel Begunkov <asml.silence@...il.com>,
        Jens Axboe <axboe@...nel.dk>, <linux-block@...r.kernel.org>,
        Omar Sandoval <osandov@...ndov.com>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/4] sbitmap: optimise sbitmap_deferred_clear()

On 22/11/2020 15:35, Pavel Begunkov wrote:
> Because of spinlocks and atomics sbitmap_deferred_clear() have to reload
> &sb->map[index] on each access even though the map address won't change.
> Pass in sbitmap_word instead of {sb, index}, so it's cached in a
> variable. It also improves code generation of
> sbitmap_find_bit_in_index().
> 
> Signed-off-by: Pavel Begunkov<asml.silence@...il.com>

Looks ok, even though a bit odd not be passing a struct sbitmap * now

Reviewed-by: John Garry <john.garry@...wei.com>