Messages in this thread | | | Date | Fri, 25 Jul 2014 17:27:28 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: make update_sd_pick_busiest return true on a busier sd |
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On Tue, Jul 22, 2014 at 02:45:59PM -0400, Rik van Riel wrote: > Currently update_sd_pick_busiest only returns true when an sd > is overloaded, or for SD_ASYM_PACKING when a domain is busier > than average and a higher numbered domain than the target. > > This breaks load balancing between domains that are not overloaded, > in the !SD_ASYM_PACKING case. This patch makes update_sd_pick_busiest > return true when the busiest sd yet is encountered. > > On a 4 node system, this seems to result in the load balancer finally > putting 1 thread of a 4 thread test run of "perf bench numa mem" on > each node, where before the load was generally not spread across all > nodes.
So for !ASYM the code is effectively:
return sgs->avg_load > sds->busiest_stat.avg_load;
I'd like to at least add a clause that makes overloaded groups prioritized over !overloaded groups.
Also, like we found earlier, calculate_imbalance() relies on the sum_nr_running > group_capacity_factor thing, which you've just 'wrecked', so we'd need an update to that part too.
> Behaviour for SD_ASYM_PACKING does not seem to match the comment, > in that groups with below average load average are ignored, but I > have no hardware to test that so I have left the behaviour of that > code unchanged.
Mikey, does that stuff work as expected?
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