linux-kernel - Re: [PATCH 29/32] block, aio: Batch completion for bios/kiocbs

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Message-ID: <x49mwwjabx2.fsf@segfault.boston.devel.redhat.com>
Date:	Tue, 08 Jan 2013 11:15:37 -0500
From:	Jeff Moyer <jmoyer@...hat.com>
To:	Kent Overstreet <koverstreet@...gle.com>
Cc:	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
	linux-aio@...ck.org, linux-fsdevel@...r.kernel.org, zab@...hat.com,
	bcrl@...ck.org, viro@...iv.linux.org.uk, tytso@....edu
Subject: Re: [PATCH 29/32] block, aio: Batch completion for bios/kiocbs

Kent Overstreet <koverstreet@...gle.com> writes:

> On Tue, Jan 08, 2013 at 10:33:18AM -0500, Jeff Moyer wrote:
>> Kent Overstreet <koverstreet@...gle.com> writes:
>> 
>> >> Is the rbtree really faster than a basic (l)list and a sort before
>> >> completing them? Would be simpler.
>> >
>> > Well, depends. With one or two kioctxs? The list would definitely be
>> > faster, but I'm loathe to use an O(n^2) algorithm anywhere where the
>> > input size isn't strictly controlled, and I know of applications out
>> > there that use tons of kioctxs.
>> 
>> Out of curiosity, what applications do you know of that use tons of
>> kioctx's?
>
> "tons" is relative I suppose, but before this patch series sharing a
> kioctx between threads was really bad for performance and... you know
> how people can be with threads.

I wasn't questioning the merits of the patch, I was simply curious to
know how aio is being (ab)used in the wild.  So, is this some internal
tool, then, or what?

Thanks!
Jeff
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