Swap with 16 Gb of RAM

Matt_Domsch@Dell.com Matt_Domsch at Dell.com
Tue Aug 21 10:23:00 CDT 2001


> I have a Dell 8450 with 16 Gb of RAM used for running biological
> computations. Currently I have 3.5 Gb of swap, and sometimes 
> it is almost
> completely used up even when only 4 Gb of RAM is used. Worse of all,
> sometimes kswapd takes up a lot of CPU time.

Yes, this is a known issue, which is being resolved only now in the latest
2.4.8 and 2.4.9 kernels.  The recommended amount of swap is 2x RAM, or in
your case, 32GB.  But, you can't actually *have* that much swap in the Red
Hat Linux 7.1 release, as you're limited to 8 swap spaces (files or
partitions) of 2047MB each.

The virtual memory subsystem has undergone a lot of changes in the 2.4.x
series.  2.4.8-ac(high-number) and/or 2.4.9 should be much better about
needing less swap, freeing no-longer-used pages from swap, and making better
use of available RAM.  If you like, you can try building a
2.4.8-ac(high-number) kernel that may perform better for you.  Or, you can
wait until Red Hat releases an errata kernel for 7.1 which may improve your
performance.

Thanks,
Matt

--
Matt Domsch
Sr. Software Engineer
Dell Linux Solutions
www.dell.com/linux
#2 Linux Server provider with 17% in the US and 14% Worldwide (IDC)!
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