Messages in this thread | | | Date | Fri, 19 Nov 2010 15:24:18 +0100 | From | Samuel Thibault <> | Subject | Re: [RFC/RFT PATCH v3] sched: automated per tty task groups |
| |
Peter Zijlstra, le Fri 19 Nov 2010 12:57:24 +0100, a écrit : > On Fri, 2010-11-19 at 01:07 +0100, Samuel Thibault wrote: > > Also note that having a hierarchical process structure should permit to > > make things globally more efficient: avoid putting e.g. your cpp, cc1, > > and asm processes at three corners of your 4-socket NUMA machine :) > > And no, using that to load-balance between CPUs doesn't necessarily help > with the NUMA case,
It doesn't _necessarily_ help, but it should help in quite a few cases.
> load-balancing is an impossible job (equivalent to > page-replacement -- you simply don't know the future), applications > simply do wildly weird stuff.
Sure. Not a reason not to get the low-hanging fruits :)
> From a process hierarchy there's absolutely no difference between a > cc1/cpp/asm and some MPI jobs, both can be parent-child relations with > pipes between, some just run short and have data affinity, others run > long and don't have any.
MPI jobs typically communicate with each other. Keeping them on the same socket permits to keep shared-memory MPI drivers to mostly remain in e.g. the L3 cache. That typically gives benefits.
Samuel -- 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/
| |