Re: Machine's high load when HIGHMEM is enabled

Brian Gerst
2002-11-03T14:26:03Z

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