Re: [patch v4 01/18] sched: set SD_PREFER_SIBLING on MC domain toreduce a domain level

From: Peter Zijlstra
Date: Fri Feb 15 2013 - 07:38:27 EST

On Wed, 2013-02-13 at 21:22 +0800, Alex Shi wrote:
> No, the flags set on MC/CPU domain, but is checked in their parents
> balancing, like in NUMA domain.
> Without the flag, will cause NUMA domain imbalance. like on my 2
> sockets
> NHM EP: 3 of 4 tasks were assigned on socket 0(lcpu, 10, 12, 14)
> In this case, update_sd_pick_busiest() need a reduced group_capacity
> to
> return true:
> if (sgs->sum_nr_running > sgs->group_capacity)
> return true;
> then numa domain balancing get chance to start.

Ah, indeed. Its always better to include such 'obvious' problems in the
changelog :-)

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