From: Matthew Wilcox <willy@infradead.org>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Benjamin LaHaise <bcrl@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH] aio: Convert ioctx_table to XArray
Date: Tue, 11 Dec 2018 09:51:56 -0800 [thread overview]
Message-ID: <20181211175156.GF6830@bombadil.infradead.org> (raw)
In-Reply-To: <x49mupcm11r.fsf@segfault.boston.devel.redhat.com>
On Tue, Dec 11, 2018 at 12:21:52PM -0500, Jeff Moyer wrote:
> I'm going to submit this version formally. If you're interested in
> converting the ioctx_table to xarray, you can do that separately from a
> security fix. I would include a performance analysis with that patch,
> though. The idea of using a radix tree for the ioctx table was
> discarded due to performance reasons--see commit db446a08c23d5 ("aio:
> convert the ioctx list to table lookup v3"). I suspect using the xarray
> will perform similarly.
There's a big difference between Octavian's patch and mine. That patch
indexed into the radix tree by 'ctx_id' directly, which was pretty
much guaranteed to exhibit some close-to-worst-case behaviour from the
radix tree due to IDs being sparsely assigned. My patch uses the ring
ID which _we_ assigned, and so is nicely behaved, being usually a very
small integer.
What performance analysis would you find compelling? Octavian's original
fio script:
> rw=randrw; size=256k ;directory=/mnt/fio; ioengine=libaio; iodepth=1
> blocksize=1024; numjobs=512; thread; loops=100
>
> on an EXT2 filesystem mounted on top of a ramdisk
or something else?
next prev parent reply other threads:[~2018-12-11 17:52 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 18:35 [PATCH] aio: Convert ioctx_table to XArray Matthew Wilcox
2018-12-06 21:08 ` Matthew Wilcox
2018-12-06 22:21 ` Jeff Moyer
2018-12-06 22:21 ` Jeff Moyer
2018-12-06 22:26 ` Jeff Moyer
2018-12-06 22:26 ` Jeff Moyer
2018-12-11 17:21 ` Jeff Moyer
2018-12-11 17:21 ` Jeff Moyer
2018-12-11 17:51 ` Matthew Wilcox [this message]
2018-12-11 18:02 ` Jeff Moyer
2018-12-11 18:02 ` Jeff Moyer
2018-12-11 18:05 ` Jens Axboe
2018-12-11 18:09 ` Jeff Moyer
2018-12-11 18:09 ` Jeff Moyer
2018-12-11 18:37 ` Jens Axboe
2018-12-11 18:32 ` Jens Axboe
2018-12-11 18:36 ` Jens Axboe
2018-12-11 18:51 ` Matthew Wilcox
2018-12-11 18:52 ` Jens Axboe
2018-12-11 18:41 ` Jens Axboe
2018-12-11 18:41 ` Jens Axboe
2018-12-11 18:45 ` Matthew Wilcox
2018-12-11 18:46 ` Jens Axboe
2018-12-11 18:53 ` Matthew Wilcox
2018-12-11 18:54 ` Jens Axboe
2018-12-11 18:53 ` Jens Axboe
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