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

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Message-ID: <6d3413c3-7cc9-8c6d-50c6-183d135a2193@gmail.com>
Date:   Tue, 24 Nov 2020 15:01:10 +0000
From:   Pavel Begunkov <asml.silence@...il.com>
To:     John Garry <john.garry@...wei.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 24/11/2020 14:11, John Garry wrote:
> 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

IMHO, narrower context is better, so looks more natural to me.

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

Thanks!

-- 
Pavel Begunkov