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

Mike Anderson
2002-03-15T23:38:17Z

John,
What kind of io controllers are on the system?

To use CONFIG_HIGHIO you need a IO controller the is physically
capable of addressing higher memory and an adapter driver that has
been converted to support the CONFIG_HIGHIO interface.

-Mike
John Helms [john.helms@photomask.com] wrote:
> Alan,
>
> Ok, how do I go about determining that? The machine
> I have is a brand-spankin' new IBM x-series 350 with
> 4 900MHz Xeon processors. The system bios can
> recognize all of the 16320MB of memory at startup.
> If those patches work, it will save our butts as
> we have a major conversion project that hinges on
> this.
>
> Thanks,
> jwh
>
> >>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
>
> On 3/15/02, 2:30:22 PM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote regarding
> Re: bug (trouble?) report on high mem support:
>
>
> > > 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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--
Michael Anderson
andmike@us.ibm.com