Messages in this thread |  | | Subject | Re: [PATCH] sched, fair: Allow a small load imbalance between low utilisation SD_NUMA domains v3 | From | Rik van Riel <> | Date | Mon, 06 Jan 2020 11:44:57 -0500 |
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On Mon, 2020-01-06 at 16:33 +0000, Mel Gorman wrote: > On Mon, Jan 06, 2020 at 10:47:18AM -0500, Rik van Riel wrote: > > > + imbalance_adj = (100 / (env->sd->imbalance_pct > > > - 100)) - 1; > > > + > > > + /* > > > + * Allow small imbalances when the busiest > > > group has > > > + * low utilisation. > > > + */ > > > + imbalance_max = imbalance_adj << 1; > > > + if (busiest->sum_nr_running < imbalance_max) > > > + env->imbalance -= min(env->imbalance, > > > imbalance_adj); > > > + } > > > + > > > > Wait, so imbalance_max is a function only of > > env->sd->imbalance_pct, and it gets compared > > against busiest->sum_nr_running, which is related > > to the number of CPUs in the node? > > > > It's not directly related to the number of CPUs in the node. Are you > thinking of busiest->group_weight?
I am, because as it is right now that if condition looks like it might never be true for imbalance_pct 115.
Presumably you put that check there for a reason, and would like it to trigger when the amount by which a node is busy is less than 2 * (imbalance_pct - 100).
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