MSI K8N Neo2 For Dual Core?

Mark Hahn hahn at physics.mcmaster.ca
Wed Aug 24 14:38:43 UTC 2005


> BTW, again, I _do_ use LVM for RAID-0 with hardware RAID.

actually, I measured this recently, and DM-raid0 is noticably slower
than MD-raid0.  I was quite surprised, since raid0 is hard to get wrong.
(I used the same stripe/chunk sizes, and did large-chunk streaming reads.)

> I span the volumes over multiple PCI-X channels on the same Opteron for
> I/O-processor affinity.

OK, so what difference do you measure between doing this (affinity vs not)?
and besides, why is the opteron on the hot path?  you're presumably just 
dma'ing big chunks of ram to/from disk, so why does 20ns inter-opteron
latency make any difference?  besides, how do you control the numa affinity 
of the pagecache?  besides, how could it matter, given that your IO is 
so vastly slower than your memory?




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