Messages in this thread Patch in this message | | | Date | Wed, 5 Jan 2022 10:49:19 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH 2/2] sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs |
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On Wed, Jan 05, 2022 at 10:42:07AM +0000, Mel Gorman wrote: > On Tue, Dec 21, 2021 at 06:13:15PM +0100, Vincent Guittot wrote: > > > <SNIP> > > > > > > @@ -9050,9 +9054,9 @@ static bool update_pick_idlest(struct sched_group *idlest, > > > * This is an approximation as the number of running tasks may not be > > > * related to the number of busy CPUs due to sched_setaffinity. > > > */ > > > -static inline bool allow_numa_imbalance(int dst_running, int dst_weight) > > > +static inline bool allow_numa_imbalance(int dst_running, int imb_numa_nr) > > > { > > > - return (dst_running < (dst_weight >> 2)); > > > + return dst_running < imb_numa_nr; > > > } > > > > > > /* > > > > > > <SNIP> > > > > > > @@ -9280,19 +9285,13 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd > > > } > > > } > > > > > > -#define NUMA_IMBALANCE_MIN 2 > > > - > > > static inline long adjust_numa_imbalance(int imbalance, > > > - int dst_running, int dst_weight) > > > + int dst_running, int imb_numa_nr) > > > { > > > - if (!allow_numa_imbalance(dst_running, dst_weight)) > > > + if (!allow_numa_imbalance(dst_running, imb_numa_nr)) > > > return imbalance; > > > > > > - /* > > > - * Allow a small imbalance based on a simple pair of communicating > > > - * tasks that remain local when the destination is lightly loaded. > > > - */ > > > - if (imbalance <= NUMA_IMBALANCE_MIN) > > > + if (imbalance <= imb_numa_nr) > > > > Isn't this always true ? > > > > imbalance is "always" < dst_running as imbalance is usually the number > > of these tasks that we would like to migrate > > > > It's not necessarily true. allow_numa_imbalanced is checking if > dst_running < imb_numa_nr and adjust_numa_imbalance is checking the > imbalance. > > imb_numa_nr = 4 > dst_running = 2 > imbalance = 1 > > In that case, imbalance of 1 is ok, but 2 is not. >
My bad, this is based on v5 which I just queued for testing.
-- Mel Gorman SUSE Labs
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