Re: bug (trouble?) report on high mem support

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Fri Mar 15 2002 - 15:30:22 EST


> Here is a top output. We have 16Gb of ram.
> I have also tried a 2.4.9-31 enterprise=20
> kernel rpm from RedHat with the same=20
> results.

Ok that would make sense. Next question is do you have an I/O controller
that can use all the 64bit address space on the PCI bus ?

What is happening is that you are using a lot of CPU copying buffers down
into lower memory to transfer to/from disk - as well probably as that
causing a lot of competition for low memory. If your I/O controller can hit
the full 64bit space there are some rather nice test patches that should
completely obliterate the problem.

Alan
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