From: Tejun Heo <tj@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>, Vivek Goyal <vgoyal@redhat.com>,
Shaohua Li <vivek.goyal2008@gmail.com>,
lkml <linux-kernel@vger.kernel.org>,
Knut Petersen <Knut_Petersen@t-online.de>,
mroos@linux.ee
Subject: Re: [PATCH] block: strip out locking optimization in put_io_context()
Date: Tue, 7 Feb 2012 08:47:35 -0800 [thread overview]
Message-ID: <20120207164735.GH21292@google.com> (raw)
In-Reply-To: <CA+55aFxcjE4FsUVoarc+8OTi4OkqtgBmHq500=qaCeTqqWnqoA@mail.gmail.com>
Hello,
On Tue, Feb 07, 2012 at 08:33:15AM -0800, Linus Torvalds wrote:
> Yeah, please just get rid of the crazy code. Maybe *that* fixes the
> regression too, who knows?
>
> For all we know, the "fast case" is what causes extra locking only to
> then fail and not even be a fast-path.
Yeah, I was about to ask Shaohua to test the version w/o optimization.
With heavily loaded request_queue, trylock failure could be frequent,
which I wasn't testing.
Shaohua, can you please test the version w/o optimization? Also, can
you please give a bit more details on the setup? Are there multiple
swap devices? Is it SSD or rotating disk?
> I think our default action should always be to simplify and clean up
> code, unless you have seriously hard numbers to show that the code
> complexity is worth it.
Sure, it was originally all in put_io_context() and while moving
things to wq, it got progressively complex and I lost sense of
complexity from staring at it too long.
Thanks.
--
tejun
next prev parent reply other threads:[~2012-02-07 16:47 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-06 7:50 [patch]block: fix ioc locking warning Shaohua Li
2012-02-06 7:55 ` Jens Axboe
2012-02-06 15:12 ` Vivek Goyal
2012-02-06 16:09 ` Jens Axboe
2012-02-06 16:37 ` Vivek Goyal
2012-02-06 16:44 ` Tejun Heo
2012-02-06 16:58 ` Linus Torvalds
2012-02-06 17:27 ` Tejun Heo
2012-02-06 20:16 ` Jens Axboe
2012-02-06 21:54 ` [PATCH] block: strip out locking optimization in put_io_context() Tejun Heo
2012-02-07 6:49 ` Jens Axboe
2012-02-07 16:22 ` Tejun Heo
2012-02-07 16:28 ` Jens Axboe
2012-02-07 16:33 ` Linus Torvalds
2012-02-07 16:47 ` Tejun Heo [this message]
2012-02-07 17:17 ` Tejun Heo
2012-02-08 0:19 ` Shaohua Li
2012-02-08 8:29 ` Shaohua Li
2012-02-08 16:29 ` Tejun Heo
2012-02-08 16:34 ` Linus Torvalds
2012-02-08 16:49 ` Tejun Heo
2012-02-08 16:56 ` Tejun Heo
2012-02-08 17:23 ` Tejun Heo
2012-02-09 6:22 ` Shaohua Li
2012-02-09 17:59 ` Tejun Heo
2012-02-09 18:07 ` Linus Torvalds
2012-02-09 19:24 ` Tejun Heo
2012-02-09 23:48 ` Tejun Heo
2012-02-10 5:14 ` Shaohua Li
2012-02-10 8:48 ` Shaohua Li
2012-02-11 2:17 ` Tejun Heo
2012-02-11 11:35 ` Jens Axboe
2012-02-13 1:34 ` Shaohua Li
2012-02-13 20:49 ` Tejun Heo
2012-02-14 2:36 ` Shaohua Li
2012-02-14 16:39 ` Tejun Heo
2012-02-10 3:09 ` Shaohua Li
2012-02-07 23:00 ` [PATCH] block: fix lockdep warning on io_context release put_io_context() Tejun Heo
2012-02-06 20:36 ` [patch]block: fix ioc locking warning Tejun Heo
2012-02-07 0:31 ` Shaohua Li
2012-02-07 0:39 ` Tejun Heo
2012-02-07 0:43 ` Shaohua Li
2012-02-07 0:59 ` Tejun Heo
2012-02-07 1:10 ` Shaohua Li
2012-02-07 1:33 ` Shaohua Li
2012-02-07 5:22 ` Shaohua Li
2012-02-07 22:34 ` Linus Torvalds
2012-02-06 16:22 ` Tejun Heo
2012-02-08 18:07 ` walt
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