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sched/fair: Reduce busy load balance interval

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The busy_factor, which increases load balance interval when a cpu is busy,
is set to 32 by default. This value generates some huge LB interval on
large system like the THX2 made of 2 node x 28 cores x 4 threads.
For such system, the interval increases from 112ms to 3584ms at MC level.
And from 228ms to 7168ms at NUMA level.

Even on smaller system, a lower busy factor has shown improvement on the
fair distribution of the running time so let reduce it for all.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/20200921072424.14813-5-vincent.guittot@linaro.org
This commit is contained in:
Vincent Guittot 2020-09-21 09:24:24 +02:00 committed by Peter Zijlstra
parent e4d32e4d54
commit 6e7499135d
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/topology.c
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@ -1348,7 +1348,7 @@ sd_init(struct sched_domain_topology_level *tl,
*sd = (struct sched_domain){
.min_interval = sd_weight,
.max_interval = 2*sd_weight,
.busy_factor = 32,
.busy_factor = 16,
.imbalance_pct = 117,
.cache_nice_tries = 0,