Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 1/1] sbitmap: Replace cmpxchg with xchg
To:     "Pavel Begunkov (Silence)" <asml.silence@gmail.com>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
References: <722e1d561f0a49dc464d3a2b1be4c077f7502726.1558625912.git.asml.silence@gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <77f4ee3b-a190-5708-f30b-0c5f2b933b3e@kernel.dk>
Date:   Mon, 1 Jul 2019 13:44:44 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.2
MIME-Version: 1.0
In-Reply-To: <722e1d561f0a49dc464d3a2b1be4c077f7502726.1558625912.git.asml.silence@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 5/23/19 9:39 AM, Pavel Begunkov (Silence) wrote:
> From: Pavel Begunkov <asml.silence@gmail.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