Re: 2.5.38-mm2 dbench $N times

Andrew Theurer
2002-09-25T21:10:51Z

On Wednesday 25 September 2002 3:57 pm, Martin J. Bligh wrote:
> > Pretty sure each dbench child does it's own write/read to only it's own
> > data. There is no sharing that I am aware of between the processes.
>
> Right, but if the processes migrate easily, there's still no CPU locality.
> Bill, do you want to try binding 1/32 of the processes to each CPU, and see
> if that makes your throughput increase?

Any stats to track migration over <x> time? Would be intersting to see this
in some sort of /proc/pid maybe?

> > How about running in tmpfs to avoid any disk IO at all?
>
> As far as I understand it, that won't help - we're operating out of
> pagecache anyway at this level, I think.

at dbench 512, that's about 512*20MB, 10GB (not 100% sure on that 20MB
figure). Have we hit a threshold at which this stuff gets written to disk?

> > Also, what's the policy for home node assignment on fork? Are all of
> > these children getting the same home node assingnment??
>
> Policy is random - the scheduler lacks any NUMA comprehension at the
> moment. The numa sched mods would probably help a lot too.

Oops, confusing this run with the numa sched stuff earlier.

Andrew Theurer