From: Andrea Arcangeli <andrea@suse.de>
To: Marcelo Tosatti <marcelo@conectiva.com.br>
Cc: Jens Axboe <axboe@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: 2.4.1pre8 slowdown on dbench tests
Date: Fri, 19 Jan 2001 01:16:29 +0100 [thread overview]
Message-ID: <20010119011629.C32087@athlon.random> (raw)
In-Reply-To: <Pine.LNX.4.21.0101181449240.4124-100000@freak.distro.conectiva>
In-Reply-To: <Pine.LNX.4.21.0101181449240.4124-100000@freak.distro.conectiva>; from marcelo@conectiva.com.br on Thu, Jan 18, 2001 at 03:17:13PM -0200
On Thu, Jan 18, 2001 at 03:17:13PM -0200, Marcelo Tosatti wrote:
> Jens, can be the -blk patch the reason for the slowdown I'm seeing?
This heuristic is way too aggressive:
/*
* Try to keep 128MB max hysteris. If not possible,
* use half of RAM
*/
high_queued_sectors = (total_ram * 2) / 3;
low_queued_sectors = high_queued_sectors - MB(128);
if (low_queued_sectors < 0)
low_queued_sectors = total_ram / 2;
/*
* for big RAM machines (>= 384MB), use more for I/O
*/
if (total_ram >= MB(384)) {
high_queued_sectors = (total_ram * 4) / 5;
low_queued_sectors = high_queued_sectors - MB(128);
}
2/3 of ram locked down in the I/O queue is way too much. 1/3 should be ok. big
RAM machines needs way less than 1/3 locked down.
Marcelo can you give a try with `high_queued_sectors = total_ram / 3' and
low_queued_sectors = high_queued_sectors / 2 and drop the big ram machine
check?
Andrea
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next prev parent reply other threads:[~2001-01-19 0:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-18 17:17 2.4.1pre8 slowdown on dbench tests Marcelo Tosatti
2001-01-18 20:18 ` Szabolcs Szakacsits
2001-01-19 2:23 ` Szabolcs Szakacsits
2001-01-19 2:13 ` Jens Axboe
2001-01-19 5:49 ` Szabolcs Szakacsits
2001-01-19 0:16 ` Andrea Arcangeli [this message]
2001-01-18 23:51 ` Marcelo Tosatti
2001-01-19 1:43 ` Jens Axboe
2001-01-19 1:40 ` Jens Axboe
2001-01-19 1:46 ` Andi Kleen
2001-01-19 1:47 ` Jens Axboe
2001-01-19 2:08 ` Andi Kleen
2001-01-19 2:10 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2001-01-18 22:52 Steven Cole
2001-01-18 21:49 ` Marcelo Tosatti
[not found] <01012208583400.01639@spc.esa.lanl.gov>
2001-01-22 20:30 ` Marcelo Tosatti
2001-01-22 23:11 ` Jens Axboe
2001-01-23 20:29 ` Steven Cole
2001-01-23 20:54 ` Jens Axboe
2001-01-24 16:08 ` Steven Cole
2001-01-24 16:44 ` Jens Axboe
2001-01-24 17:03 ` Steven Cole
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