Re: severe I/O performance issues on 2.4.22 SMP system
On Sat, Nov 01, 2003 at 08:37:42AM +1100, Russell Coker wrote:
> On Sat, 1 Nov 2003 07:38, Daniel Erat wrote:
> > The server has a SuperMicro Super P4DP6 motherboard with dual Xeon
> > 2.4Ghz processors and 4 GB of RAM. One of the two onboard Adaptec
> > 7899P SCSI chipsets is being used to control a disk that has the OS,
> > and a
>
> My experience is that the kernel.org kernel performs very badly under
> heavy disk IO when you have 4G of RAM. There are patches to fix this,
> I can't remember which ones they are (and I couldn't find the patches
> on their own when I looked).
>
> I solved this before by using a SUSE kernel source tree, but a Red Hat
> kernel source tree has the same patches.
Thanks! I'm hesistant to switch to the SUSE or Red Hat source trees
because of the large number of changes there. If I just want to work
around the problem so I can finally get some sleep, do you know if I can
pull a gig of memory out of the machine, or will I need to instead or
additionally recompile the kernel without 4 GB High Memory Support? In
other words, is this some sort of boundary condition that's triggered
when the kernel is working near the 32-bit 4 GB limit, or is it a more
general problem in the 4 GB High Memory Support option that will crop up
regardless of how much physical memory is actually in the server?
Dan
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