Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
Message-ID: <471e5654-49d7-9023-62b4-fc98483b1d89@kernel.dk>
Date:   Fri, 20 May 2022 16:18:06 -0600
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101
 Thunderbird/91.8.1
Subject: Re: [PATCH] fs: prefer read_iter over read and write_iter over write
Content-Language: en-US
To:     David Laight <David.Laight@ACULAB.COM>,
        "'Jason A. Donenfeld'" <Jason@zx2c4.com>
Cc:     "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20220520135103.166972-1-Jason@zx2c4.com>
 <39ed6917f2e64a07bad8dad63f8dceb4@AcuMS.aculab.com>
 <YogIg9FG7C/f98bf@zx2c4.com>
 <0da16e16caed4282ae97a86f1ba6f6db@AcuMS.aculab.com>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <0da16e16caed4282ae97a86f1ba6f6db@AcuMS.aculab.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 5/20/22 4:08 PM, David Laight wrote:
>>    https://lore.kernel.org/lkml/Yoey+FOYO69lS5qP@zx2c4.com/
>>
>> The hope is that it eventually becomes faster... :-\
> 
> I suspect all the xxx_iter functions need optimising for
> the common case of a single buffer in userspace.
> 
> That also includes the code to read the iov[] from usespace.
> At the moment I think the 32bit compat code is actually
> faster than the native amd64 version!
> I've written some patches to speed that up.
> But the bigger improvements all hit massive changes
> to the ioring code.

Do you have a link to those patches? I can certainly help with the
io_uring side of things, and I have a genuine interest in improving the
core and getting the iter side up to snuff.

-- 
Jens Axboe