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| author | Tim Chen <tim.c.chen@linux.intel.com> | 2023-09-07 10:42:21 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2023-09-13 15:03:06 +0200 |
| commit | 450e749707bc1755f22b505d9cd942d4869dc535 (patch) | |
| tree | c5bba96bc95d14a8679acc9fd1420e595a525e30 | |
| parent | f8858d96061f5942216c6abb0194c3ea7b78e1e8 (diff) | |
| download | linux-450e749707bc1755f22b505d9cd942d4869dc535.tar.gz | |
sched/fair: Fix SMT4 group_smt_balance handling
For SMT4, any group with more than 2 tasks will be marked as
group_smt_balance. Retain the behaviour of group_has_spare by marking
the busiest group as the group which has the least number of idle_cpus.
Also, handle rounding effect of adding (ncores_local + ncores_busy) when
the local is fully idle and busy group imbalance is less than 2 tasks.
Local group should try to pull at least 1 task in this case so imbalance
should be set to 2 instead.
Fixes: fee1759e4f04 ("sched/fair: Determine active load balance for SMT sched groups")
Acked-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/6cd1633036bb6b651af575c32c2a9608a106702c.camel@linux.intel.com
| -rw-r--r-- | kernel/sched/fair.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 33a2b6bba676a8..cb225921bbca47 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9580,7 +9580,7 @@ static inline long sibling_imbalance(struct lb_env *env, imbalance /= ncores_local + ncores_busiest; /* Take advantage of resource in an empty sched group */ - if (imbalance == 0 && local->sum_nr_running == 0 && + if (imbalance <= 1 && local->sum_nr_running == 0 && busiest->sum_nr_running > 1) imbalance = 2; @@ -9768,6 +9768,15 @@ static bool update_sd_pick_busiest(struct lb_env *env, break; case group_smt_balance: + /* + * Check if we have spare CPUs on either SMT group to + * choose has spare or fully busy handling. + */ + if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0) + goto has_spare; + + fallthrough; + case group_fully_busy: /* * Select the fully busy group with highest avg_load. In @@ -9807,6 +9816,7 @@ static bool update_sd_pick_busiest(struct lb_env *env, else return true; } +has_spare: /* * Select not overloaded group with lowest number of idle cpus |