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| author | Valentin Schneider <valentin.schneider@arm.com> | 2020-02-27 19:14:32 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-03-06 12:57:23 +0100 |
| commit | 38502ab4bf3c463081bfd53356980a9ec2f32d1d (patch) | |
| tree | 6c352256955a8885a816b59253cc5434ba7c289e /kernel/sched | |
| parent | 0621df315402dd7bc56f7272fae9778701289825 (diff) | |
| download | linux-38502ab4bf3c463081bfd53356980a9ec2f32d1d.tar.gz | |
sched/topology: Don't enable EAS on SMT systems
EAS already requires asymmetric CPU capacities to be enabled, and mixing this with SMT is an aberration, but better be safe than sorry. Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Acked-by: Quentin Perret <qperret@google.com> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200227191433.31994-2-valentin.schneider@arm.com
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/topology.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 00911884b7e7..8344757bba6e 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -317,8 +317,9 @@ static void sched_energy_set(bool has_eas) * EAS can be used on a root domain if it meets all the following conditions: * 1. an Energy Model (EM) is available; * 2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy. - * 3. the EM complexity is low enough to keep scheduling overheads low; - * 4. schedutil is driving the frequency of all CPUs of the rd; + * 3. no SMT is detected. + * 4. the EM complexity is low enough to keep scheduling overheads low; + * 5. schedutil is driving the frequency of all CPUs of the rd; * * The complexity of the Energy Model is defined as: * @@ -360,6 +361,13 @@ static bool build_perf_domains(const struct cpumask *cpu_map) goto free; } + /* EAS definitely does *not* handle SMT */ + if (sched_smt_active()) { + pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n", + cpumask_pr_args(cpu_map)); + goto free; + } + for_each_cpu(i, cpu_map) { /* Skip already covered CPUs. */ if (find_pd(pd, i)) |