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. Reviewed-by: Phil Auld <[email protected]> Signed-off-by: Vincent Guittot <[email protected]> --- kernel/sched/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 41df62884cea..a3a2417fec54 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -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, -- 2.17.1
