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

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