Messages in this thread | | | Date | Sun, 3 Apr 2005 15:30:56 -0700 | From | Paul Jackson <> | Subject | Re: [patch] sched: auto-tune migration costs [was: Re: Industry db benchmark result on recent 2.6 kernels] |
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Ingo wrote: > if_ there is a significant hierarchy between CPUs it > should be represented via a matching sched-domains hierarchy,
Agreed.
I'll see how the sched domains hierarchy looks on a bigger SN2 systems.
If the CPU hierarchy is not reflected in the sched-domain hierarchy any better there, then I will look to involve the "SN2 sched domain hierarchy experts" in improving SN2 the sched-domain hierarchy.
Ok - that works. Your patch of yesterday provides just the tool I need to measure this. Cool.
> i'll first try the bottom-up approach to speed up detection (getting to > the hump is very fast most of the time).
Good.
> then we can let the arch override the cpu_distance() method
I'm not aware we need that, yet anyway. First I should see if the SN2 sched_domains need improving. Take a shot at doing it 'the right way' before we go inventing overrides. I suspect you agree.
> the migration cost matrix we can later use to tune all the other > sched-domains balancing related tunables as well
That comes close to my actual motivation here. I hope to expose a "cpu_distance" such as based on this cost matrix, to userland.
We already expose the SLIT table node distances (using SN2 specific /proc files today, others are working on an arch-neutral mechanism).
As we push more cores and hyperthreads into a single package on one end, and more complex numa topologies on the other end, this becomes increasingly interesting to NUMA aware user software.
-- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <pj@engr.sgi.com> 1.650.933.1373, 1.925.600.0401 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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