diff options
| author | Vincent Guittot <[email protected]> | 2020-09-21 09:24:22 +0200 |
|---|---|---|
| committer | Peter Zijlstra <[email protected]> | 2020-09-25 14:23:26 +0200 |
| commit | 2208cdaa56c957e20d8e16f28819aeb47851cb1e (patch) | |
| tree | e11fdea39f71c5ecb6e9a0d7f3a5e4db2cd7f39a | |
| parent | 5a7f555904671c0737819fe4d19bd6143de3f6c0 (diff) | |
sched/fair: Reduce minimal imbalance threshold
The 25% default imbalance threshold for DIE and NUMA domain is large
enough to generate significant unfairness between threads. A typical
example is the case of 11 threads running on 2x4 CPUs. The imbalance of
20% between the 2 groups of 4 cores is just low enough to not trigger
the load balance between the 2 groups. We will have always the same 6
threads on one group of 4 CPUs and the other 5 threads on the other
group of CPUS. With a fair time sharing in each group, we ends up with
+20% running time for the group of 5 threads.
Consider decreasing the imbalance threshold for overloaded case where we
use the load to balance task and to ensure fair time sharing.
Signed-off-by: Vincent Guittot <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Phil Auld <[email protected]>
Acked-by: Hillf Danton <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
| -rw-r--r-- | kernel/sched/topology.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 249bec7b0a4c..41df62884cea 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1349,7 +1349,7 @@ sd_init(struct sched_domain_topology_level *tl, .min_interval = sd_weight, .max_interval = 2*sd_weight, .busy_factor = 32, - .imbalance_pct = 125, + .imbalance_pct = 117, .cache_nice_tries = 0, |