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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-09-01 10:34:35 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-04 10:09:54 +0200
commita52bfd73589eaf88d9c95ad2c1de0b38a6b27972 (patch)
tree33cee609a46624525abf1643d71d0fbc79e25f87 /kernel
parentcc9fba7d7672fa3ed58d9d9ecb6c45b1351c29a6 (diff)
sched: Add smt_gain
The idea is that multi-threading a core yields more work capacity than a single thread, provide a way to express a static gain for threads. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Gautham R Shenoy <ego@in.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> LKML-Reference: <20090901083826.073345955@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index ecb4a47d421..55112261027 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8523,9 +8523,15 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
weight = cpumask_weight(sched_domain_span(sd));
/*
* SMT siblings share the power of a single core.
+ * Usually multiple threads get a better yield out of
+ * that one core than a single thread would have,
+ * reflect that in sd->smt_gain.
*/
- if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1)
+ if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
+ power *= sd->smt_gain;
power /= weight;
+ power >>= SCHED_LOAD_SHIFT;
+ }
sg_inc_cpu_power(sd->groups, power);
return;
}