Messages in this thread | | | Subject | Re: [PATCH] sched: make update_sd_pick_busiest return true on a busier sd | From | Michael Neuling <> | Date | Mon, 28 Jul 2014 09:57:57 +1000 |
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On Fri, 2014-07-25 at 17:27 +0200, Peter Zijlstra wrote: > 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?
Sorry for the slow response. v1 and v2 both pass testing on POWER7. So FWIW...
Acked-By: Michael Neuling <mikey@neuling.org>
Mikey
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