linux-kernel - Re: [PATCH 1/1] sbitmap: Replace cmpxchg with xchg

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Message-ID: <77f4ee3b-a190-5708-f30b-0c5f2b933b3e@kernel.dk>
Date:   Mon, 1 Jul 2019 13:44:44 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     "Pavel Begunkov (Silence)" <asml.silence@...il.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] sbitmap: Replace cmpxchg with xchg

On 5/23/19 9:39 AM, Pavel Begunkov (Silence) wrote:
> From: Pavel Begunkov <asml.silence@...il.com>
> 
> cmpxchg() with an immediate value could be replaced with less expensive
> xchg(). The same true if new value don't _depend_ on the old one.
> 
> In the second block, atomic_cmpxchg() return value isn't checked, so
> after atomic_cmpxchg() ->  atomic_xchg() conversion it could be replaced
> with atomic_set(). Comparison with atomic_read() in the second chunk was
> left as an optimisation (if that was the initial intention).

Applied, thanks.

-- 
Jens Axboe