From: Nick Piggin <piggin@cyberone.com.au>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Chris Mason <mason@suse.com>,
Marc-Christian Petersen <m.c.p@wolk-project.de>,
Jens Axboe <axboe@suse.de>,
Marcelo Tosatti <marcelo@conectiva.com.br>,
Georg Nikodym <georgn@somanetworks.com>,
lkml <linux-kernel@vger.kernel.org>,
Matthias Mueller <matthias.mueller@rz.uni-karlsruhe.de>
Subject: Re: [PATCH] io stalls
Date: Thu, 12 Jun 2003 13:04:27 +1000 [thread overview]
Message-ID: <3EE7EDBB.70608@cyberone.com.au> (raw)
In-Reply-To: <20030612025812.GF1415@dualathlon.random>
Andrea Arcangeli wrote:
>On Thu, Jun 12, 2003 at 12:49:46PM +1000, Nick Piggin wrote:
>
>>
>>Andrea Arcangeli wrote:
>>
>>>it does nothing w/ _exclusive and w/o the wake_up_nr, that's why I added
>>>the wake_up_nr.
>>>
>>>
>>>
>>That is pretty pointless as well. You might as well just start
>>waking up at the queue full limit, and wake one at a time.
>>
>>The purpose for batch_requests was I think for devices with a
>>very small request size, to reduce context switches.
>>
>
>batch_requests at least in my tree matters only when each request is
>512btyes and you've some thousand of them to compose a 4M queue or so.
>To maximize cpu cache usage etc.. I try to wakeup a task every 512bytes
>written, but every 32*512bytes written or so. Of course w/o the
>wake_up_nr that I added, that wasn't really working w/ the _exlusive
>wakeup.
>
>if you check my tree you'll see that for sequential I/O with 512k in
>each request (not 512bytes!) batch_requests is already a noop.
>
You are waking up multiple tasks which will each submit
1 request. You want to be waking up 1 task which will
submit multiple requests - that is how you will save
context switches, cpu cache, etc, and that task's requests
will have a much better chance of being merged, or at
least serviced as a nice batch than unrelated tasks.
next prev parent reply other threads:[~2003-06-12 2:51 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-29 0:55 Linux 2.4.21-rc6 Marcelo Tosatti
2003-05-29 1:22 ` Con Kolivas
2003-05-29 5:24 ` Marc Wilson
2003-05-29 5:34 ` Riley Williams
2003-05-29 5:57 ` Marc Wilson
2003-05-29 7:15 ` Riley Williams
2003-05-29 8:38 ` Willy Tarreau
2003-05-29 8:40 ` Willy Tarreau
2003-06-03 16:02 ` Marcelo Tosatti
2003-06-03 16:13 ` Marc-Christian Petersen
2003-06-04 21:54 ` Pavel Machek
2003-06-05 2:10 ` Michael Frank
2003-06-03 16:30 ` Michael Frank
2003-06-03 16:53 ` Matthias Mueller
2003-06-03 16:59 ` Marc-Christian Petersen
2003-06-03 17:03 ` Marc-Christian Petersen
2003-06-03 18:02 ` Anders Karlsson
2003-06-03 21:12 ` J.A. Magallon
2003-06-03 21:18 ` Marc-Christian Petersen
2003-06-03 17:23 ` Michael Frank
2003-06-04 14:56 ` Jakob Oestergaard
2003-06-04 4:04 ` Marc Wilson
2003-05-29 10:02 ` Con Kolivas
2003-05-29 18:00 ` Georg Nikodym
2003-05-29 19:11 ` -rc7 " Marcelo Tosatti
2003-05-29 19:56 ` Krzysiek Taraszka
2003-05-29 20:18 ` Krzysiek Taraszka
2003-06-04 18:17 ` Marcelo Tosatti
2003-06-04 21:41 ` Krzysiek Taraszka
2003-06-04 22:37 ` Alan Cox
2003-06-04 10:22 ` Andrea Arcangeli
2003-06-04 10:35 ` Marc-Christian Petersen
2003-06-04 10:42 ` Jens Axboe
2003-06-04 10:46 ` Marc-Christian Petersen
2003-06-04 10:48 ` Andrea Arcangeli
2003-06-04 11:57 ` Nick Piggin
2003-06-04 12:00 ` Jens Axboe
2003-06-04 12:09 ` Andrea Arcangeli
2003-06-04 12:20 ` Jens Axboe
2003-06-04 20:50 ` Rob Landley
2003-06-04 12:11 ` Nick Piggin
2003-06-04 12:35 ` Miquel van Smoorenburg
2003-06-09 21:39 ` [PATCH] io stalls (was: -rc7 Re: Linux 2.4.21-rc6) Chris Mason
2003-06-09 22:19 ` Andrea Arcangeli
2003-06-10 0:27 ` Chris Mason
2003-06-10 23:13 ` Chris Mason
2003-06-11 0:16 ` Andrea Arcangeli
2003-06-11 0:44 ` Chris Mason
2003-06-09 23:51 ` [PATCH] io stalls Nick Piggin
2003-06-10 0:32 ` Chris Mason
2003-06-10 0:47 ` Nick Piggin
2003-06-10 1:48 ` Robert White
2003-06-10 2:13 ` Chris Mason
2003-06-10 23:04 ` Robert White
2003-06-11 0:58 ` Chris Mason
2003-06-10 3:22 ` Nick Piggin
2003-06-10 21:17 ` Robert White
2003-06-11 0:40 ` Nick Piggin
2003-06-11 0:33 ` [PATCH] io stalls (was: -rc7 Re: Linux 2.4.21-rc6) Andrea Arcangeli
2003-06-11 0:48 ` [PATCH] io stalls Nick Piggin
2003-06-11 1:07 ` Andrea Arcangeli
2003-06-11 0:54 ` [PATCH] io stalls (was: -rc7 Re: Linux 2.4.21-rc6) Chris Mason
2003-06-11 1:06 ` Andrea Arcangeli
2003-06-11 1:57 ` Chris Mason
2003-06-11 2:10 ` Andrea Arcangeli
2003-06-11 12:24 ` Chris Mason
2003-06-11 17:42 ` Chris Mason
2003-06-11 18:12 ` Andrea Arcangeli
2003-06-11 18:27 ` Chris Mason
2003-06-11 18:35 ` Andrea Arcangeli
2003-06-12 1:04 ` [PATCH] io stalls Nick Piggin
2003-06-12 1:12 ` Chris Mason
2003-06-12 1:29 ` Andrea Arcangeli
2003-06-12 1:37 ` Andrea Arcangeli
2003-06-12 2:22 ` Chris Mason
2003-06-12 2:41 ` Nick Piggin
2003-06-12 2:46 ` Andrea Arcangeli
2003-06-12 2:49 ` Nick Piggin
2003-06-12 2:51 ` Nick Piggin
2003-06-12 2:52 ` Nick Piggin
2003-06-12 3:04 ` Andrea Arcangeli
2003-06-12 2:58 ` Andrea Arcangeli
2003-06-12 3:04 ` Nick Piggin [this message]
2003-06-12 3:12 ` Andrea Arcangeli
2003-06-12 3:20 ` Nick Piggin
2003-06-12 3:33 ` Andrea Arcangeli
2003-06-12 3:48 ` Nick Piggin
2003-06-12 4:17 ` Andrea Arcangeli
2003-06-12 4:41 ` Nick Piggin
2003-06-12 16:06 ` Chris Mason
2003-06-12 16:16 ` Nick Piggin
2003-06-25 19:03 ` Chris Mason
2003-06-25 19:25 ` Andrea Arcangeli
2003-06-25 20:18 ` Chris Mason
2003-06-27 8:41 ` write-caches, I/O stalls: MUST-FIX (was: [PATCH] io stalls) Matthias Andree
2003-06-26 5:48 ` [PATCH] io stalls Nick Piggin
2003-06-26 11:48 ` Chris Mason
2003-06-26 13:04 ` Nick Piggin
2003-06-26 13:18 ` Nick Piggin
2003-06-26 15:55 ` Chris Mason
2003-06-27 1:21 ` Nick Piggin
2003-06-27 1:39 ` Chris Mason
2003-06-27 9:45 ` Nick Piggin
2003-06-27 12:41 ` Chris Mason
2003-06-12 11:57 ` Chris Mason
2003-06-04 10:43 ` -rc7 Re: Linux 2.4.21-rc6 Andrea Arcangeli
2003-06-04 11:01 ` Marc-Christian Petersen
2003-06-03 19:45 ` Config issue (CONFIG_X86_TSC) " Paul
2003-06-03 20:18 ` Jan-Benedict Glaw
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