From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Theodore Ts'o <tytso@mit.edu>, Christoph Hellwig <hch@lst.de>,
LKML <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v4 0/3] random: convert to using iters, for Al Viro
Date: Fri, 20 May 2022 17:39:40 +0200 [thread overview]
Message-ID: <Yoe2PPA/pzqhf+GZ@zx2c4.com> (raw)
In-Reply-To: <bbdeeca7-9c99-e661-6596-f04ea783a30b@kernel.dk>
Hi Jens,
On Fri, May 20, 2022 at 09:34:46AM -0600, Jens Axboe wrote:
> On 5/20/22 9:25 AM, Jason A. Donenfeld wrote:
> > Hi Jens,
> >
> > On Fri, May 20, 2022 at 11:44:56AM +0200, Jason A. Donenfeld wrote:
> >> Jens Axboe (3):
> >> random: convert to using fops->read_iter()
> >> random: convert to using fops->write_iter()
> >> random: wire up fops->splice_{read,write}_iter()
> >
> > FYI, this series makes reads from /dev/urandom slower, from around 616
> > MiB/s to 598 MiB/s on my system. That seems rather unfortunate.
>
> How reproducible is that? That seems like a huge difference for the
> change. How big are the reads?
Fairly reproducible. Actually, if anything, it reproduces consistently
with worst results; I chose the most favorable ones for the new code.
This isn't any fancy `perf` profiling, but just running:
$ pv /dev/urandom > /dev/null
From looking at strace, the read size appears to be 131072.
Jason
next prev parent reply other threads:[~2022-05-20 15:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-20 9:44 [PATCH v4 0/3] random: convert to using iters, for Al Viro Jason A. Donenfeld
2022-05-20 9:44 ` [PATCH v4 1/3] random: convert to using fops->read_iter() Jason A. Donenfeld
2022-05-20 13:37 ` Jason A. Donenfeld
2022-05-20 14:36 ` Jens Axboe
2022-05-20 14:39 ` Jason A. Donenfeld
2022-05-20 15:12 ` Al Viro
2022-05-20 9:44 ` [PATCH v4 2/3] random: convert to using fops->write_iter() Jason A. Donenfeld
2022-05-20 9:44 ` [PATCH v4 3/3] random: wire up fops->splice_{read,write}_iter() Jason A. Donenfeld
2022-05-20 12:16 ` [PATCH v4 0/3] random: convert to using iters, for Al Viro Jens Axboe
2022-05-20 15:25 ` Jason A. Donenfeld
2022-05-20 15:34 ` Jens Axboe
2022-05-20 15:39 ` Jason A. Donenfeld [this message]
2022-05-20 15:44 ` Jens Axboe
2022-05-20 15:55 ` Jason A. Donenfeld
2022-05-20 15:58 ` Jens Axboe
2022-05-20 16:03 ` Jason A. Donenfeld
2022-05-20 16:06 ` Jens Axboe
2022-05-20 15:46 ` Jason A. Donenfeld
2022-05-20 15:51 ` Jens Axboe
2022-05-20 15:58 ` Jason A. Donenfeld
2022-05-20 16:00 ` Jens Axboe
2022-05-20 15:47 ` Al Viro
2022-05-20 15:53 ` Jens Axboe
2022-05-20 16:15 ` Al Viro
2022-05-20 16:24 ` Jens Axboe
2022-05-20 16:39 ` Jason A. Donenfeld
2022-05-20 16:41 ` Jens Axboe
2022-05-24 4:52 ` Eric W. Biederman
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