From: Nick Piggin <piggin@cyberone.com.au>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Hans Reiser <reiser@namesys.com>, Andrew Morton <akpm@digeo.com>,
jakob@unthought.net, david.lang@digitalinsight.com,
riel@conectiva.com.br, ckolivas@yahoo.com.au,
linux-kernel@vger.kernel.org, axboe@suse.de
Subject: Re: stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest]
Date: Mon, 10 Feb 2003 23:36:50 +1100 [thread overview]
Message-ID: <3E479CE2.5090605@cyberone.com.au> (raw)
In-Reply-To: 20030210122248.GG31401@dualathlon.random
Andrea Arcangeli wrote:
>On Mon, Feb 10, 2003 at 11:11:01PM +1100, Nick Piggin wrote:
>
>>I don't understand it at all. I mean there is no other IO going
>>
>
>Unfortunately I can't help you understand it, but this is what I found
>with my pratical experience, I found it the first time in my alpha years
>ago when I increased the sym to 512k in early 2.4 then since it could
>break stuff we added the max_sectors again in 2.4. But of course if you
>don't fix readahead there's no way reads can take advantage of these
>lowlevel fixes. I thought I fixed readahead too but I felt it got backed
>out and when I noticed I resurrected it in my tree (see the name of the
>patch ;)
>
Fair enough. I accept it is important. Still think its odd ;)
[snip]
>>It would be easy to anticipate or not based on hints. We could
>>
>
>yep.
>
>
>>anticipate sync writes if we wanted, lower expire time for sync
>>writes, increase it for async reads. It is really not very
>>complex (although the code needs tidying up).
>>
>
>this is not the way I thought at it. I'm interested to give an hint
>only to know for sure which are the intermediate sync dependent reads
>(the obvious example is when doing the get_block and walking the
>3 level of inode indirect metadata blocks with big files, or while
>walking the balanced tree in reiserfs), and I'm not interested at all
>about writes. And I would just set an higher timeout when a read that I
>know for sure (thanks to the hint) is "intermdiate" is completed. We can
>use high timeouts there because we know they won't trigger 90% of the
>time, a new dependent read will be always submitted first.
>
This is a lot of nitty gritty stuff. It will all help, especially
in corner cases. Luckily it seems you don't need such
infrastructure to demonstrate most anticipatory scheduler gains.
next prev parent reply other threads:[~2003-02-10 12:27 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-09 13:30 [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest Con Kolivas
2003-02-09 14:46 ` stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest] Andrea Arcangeli
2003-02-10 3:13 ` Nick Piggin
2003-02-10 3:52 ` Rik van Riel
2003-02-10 4:44 ` Nick Piggin
2003-02-10 5:15 ` usbaudio.c 2.5.59 John
2003-02-10 7:26 ` stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest] Andrea Arcangeli
2003-02-10 7:43 ` Nick Piggin
2003-02-10 3:42 ` Rik van Riel
2003-02-10 4:15 ` Rik van Riel
2003-02-10 4:19 ` David Lang
2003-02-10 4:29 ` Rik van Riel
2003-02-10 7:20 ` Andrea Arcangeli
2003-02-10 4:33 ` Andrew Morton
2003-02-10 4:47 ` Rik van Riel
2003-02-10 7:31 ` Andrea Arcangeli
2003-02-10 4:51 ` Jakob Oestergaard
2003-02-10 4:58 ` Nick Piggin
2003-02-10 5:10 ` Jakob Oestergaard
2003-02-10 6:06 ` Valdis.Kletnieks
2003-02-10 6:31 ` Jakob Oestergaard
2003-02-10 7:36 ` Andrea Arcangeli
2003-02-10 7:41 ` Nick Piggin
2003-02-10 8:08 ` Andrea Arcangeli
2003-02-10 8:19 ` Andrew Morton
2003-02-10 8:56 ` Andrea Arcangeli
2003-02-10 9:09 ` Andrew Morton
2003-02-10 9:14 ` Andrea Arcangeli
2003-02-10 10:07 ` Hans Reiser
2003-02-10 10:15 ` Andrea Arcangeli
2003-02-10 10:40 ` Nick Piggin
2003-02-10 11:10 ` Andrea Arcangeli
2003-02-10 11:21 ` Andrew Morton
2003-02-10 11:31 ` Andrea Arcangeli
2003-02-10 11:24 ` Nick Piggin
2003-02-10 11:39 ` Andrea Arcangeli
2003-02-10 11:45 ` Nick Piggin
2003-02-10 12:00 ` Andrea Arcangeli
2003-02-10 12:11 ` Nick Piggin
2003-02-10 12:22 ` Andrea Arcangeli
2003-02-10 12:36 ` Nick Piggin [this message]
2003-02-10 12:47 ` Andrea Arcangeli
2003-02-10 13:26 ` Rik van Riel
2003-02-10 11:48 ` Andrew Morton
2003-02-10 11:53 ` Nick Piggin
2003-02-10 12:10 ` Andrea Arcangeli
2003-02-10 12:14 ` Nick Piggin
2003-02-10 12:26 ` Andrea Arcangeli
2003-02-10 12:12 ` Andrew Morton
2003-02-10 12:25 ` Andrea Arcangeli
2003-02-10 12:27 ` Nick Piggin
2003-02-10 12:30 ` Andrea Arcangeli
2003-02-10 12:34 ` Nick Piggin
2003-02-10 12:43 ` Andrea Arcangeli
2003-02-10 12:55 ` Nick Piggin
2003-02-10 13:30 ` Rik van Riel
2003-02-11 19:13 ` Rod Van Meter
2003-02-10 12:09 ` Andrea Arcangeli
2003-02-10 12:17 ` Nick Piggin
2003-02-10 12:28 ` Andrea Arcangeli
2003-02-10 12:58 ` Hans Reiser
2003-02-10 13:18 ` Andrea Arcangeli
2003-02-10 20:14 ` Hans Reiser
2003-02-10 13:19 ` Nick Piggin
2003-02-10 14:49 ` stochastic fair queueing in the elevator [Re: [BENCHMARK] 2 Giuliano Pochini
2003-02-10 15:05 ` Andrea Arcangeli
2003-02-10 11:25 ` stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest] Hans Reiser
2003-02-10 11:42 ` Andrew Morton
2003-02-10 13:00 ` Hans Reiser
2003-02-10 10:48 ` Andrew Morton
2003-02-10 10:55 ` Nick Piggin
2003-02-10 11:21 ` Andrea Arcangeli
2003-02-10 11:33 ` Andrew Morton
2003-02-10 11:43 ` Andrea Arcangeli
2003-02-10 11:39 ` Nick Piggin
2003-02-10 9:59 ` Hans Reiser
2003-02-10 10:06 ` Andrew Morton
2003-02-10 10:17 ` Hans Reiser
2003-02-10 10:39 ` Hans Reiser
2003-02-10 8:27 ` Nick Piggin
2003-02-10 9:02 ` Andrea Arcangeli
2003-02-10 9:18 ` Nick Piggin
2003-02-10 20:33 ` Kurt Garloff
2003-02-10 21:43 ` Rik van Riel
2003-02-10 5:01 ` Andrew Morton
2003-02-10 7:34 ` Andrea Arcangeli
2003-02-10 4:44 ` Rik van Riel
2003-02-10 7:31 ` Andrea Arcangeli
2003-02-10 7:17 ` Andrea Arcangeli
2003-02-10 7:39 ` Nick Piggin
2003-02-10 10:03 ` stochastic fair queueing in the elevator [Re: [BENCHMARK] 2 Giuliano Pochini
2003-02-10 16:23 ` stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest] Pavel Machek
2003-02-11 11:49 ` Andrea Arcangeli
2003-02-11 12:43 ` Jens Axboe
2003-02-11 14:28 ` Jason Lunz
2003-02-11 14:41 ` Jens Axboe
2003-02-11 17:17 ` Jason Lunz
2003-02-11 20:19 ` Jens Axboe
2003-02-10 16:47 ` Pavel Machek
2003-02-11 11:01 ` Jens Axboe
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