Re: Machine's high load when HIGHMEM is enabled

Brian Gerst (bgerst@didntduck.org)
Sun, 03 Nov 2002 09:32:28 -0500

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


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/