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From: Brian Gerst <bgerst@quark.didntduck.org>
To: vasya vasyaev <vasya197@yahoo.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Machine's high load when HIGHMEM is enabled
Date: Sun, 03 Nov 2002 09:32:28 -0500	[thread overview]
Message-ID: <3DC5337C.4090506@quark.didntduck.org> (raw)
In-Reply-To: 20021103141753.50480.qmail@web20503.mail.yahoo.com

vasya vasyaev wrote:
> Hello,
> 
> I have some strange kind of problem:
> When HIGHMEM-enabled kernel is used, there is too high
> CPU load on any task - computer get loaded high while
> it is doing some minor, usual jobs (load average grows
> significantly).

2.4 can only do I/O to and from lowmem.  This means highmem pages have 
to use bounce buffers in lowmem, and th edata is copied to/from highmem 
which is causing the cpu load.  This has been corrected in 2.5, which 
can do I/O to any page the device can DMA from.

--
				Brian Gerst


  reply	other threads:[~2002-11-03 14:26 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-11-03 14:17 Machine's high load when HIGHMEM is enabled vasya vasyaev
2002-11-03 14:32 ` Brian Gerst [this message]
2002-11-03 15:00   ` Jens Axboe
2002-11-04  0:43     ` Denis Vlasenko
2002-11-04 18:54   ` vasya vasyaev
2002-11-04 19:27     ` Andrew Morton
2002-11-05 10:36       ` vasya vasyaev
2002-11-03 15:28 ` Martin J. Bligh
  -- strict thread matches above, loose matches on Subject: below --
2002-11-04 19:49 Nakajima, Jun
2002-11-05  9:08 ` vasya vasyaev
2002-11-05 21:10 ` vasya vasyaev
2002-11-05 21:38 Nakajima, Jun
2002-11-06 10:14 ` vasya vasyaev
2002-11-06 16:51   ` Andrew Morton
2002-11-06 17:10     ` Dave Jones
2002-11-19  9:29     ` vasya vasyaev
2002-11-19  9:40       ` Andrew Morton
2002-11-20  1:03         ` Gerrit Huizenga
2002-11-19 15:35       ` Martin J. Bligh

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