diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-10-22 18:07:47 +0530 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2009-10-29 09:08:24 +0100 |
| commit | 581d1c646e0504492bff3e97a113eba7ec8b40a3 (patch) | |
| tree | 95dee7fb83a26f85b46daa02ada3d82cdf0e9185 | |
| parent | 337946f84f00487e20e4bc946ac272afeb3256c7 (diff) | |
| download | lwn-581d1c646e0504492bff3e97a113eba7ec8b40a3.tar.gz lwn-581d1c646e0504492bff3e97a113eba7ec8b40a3.zip | |
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.
[ dino: backport to 31-rt ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: John Kacur <jkacur@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | include/linux/sched.h | 1 | ||||
| -rw-r--r-- | include/linux/topology.h | 1 | ||||
| -rw-r--r-- | kernel/sched.c | 8 |
3 files changed, 9 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 42b302f12392..09dea08f4d8c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -966,6 +966,7 @@ struct sched_domain { unsigned int newidle_idx; unsigned int wake_idx; unsigned int forkexec_idx; + unsigned int smt_gain; int flags; /* See SD_* */ enum sched_domain_level level; diff --git a/include/linux/topology.h b/include/linux/topology.h index 7402c1a27c4f..6203ae5067ce 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -99,6 +99,7 @@ int arch_update_cpu_topology(void); | SD_SHARE_CPUPOWER, \ .last_balance = jiffies, \ .balance_interval = 1, \ + .smt_gain = 1178, /* 15% */ \ } #endif #endif /* CONFIG_SCHED_SMT */ diff --git a/kernel/sched.c b/kernel/sched.c index e5b344b5b89e..9c750e363b96 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -8729,9 +8729,15 @@ 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; } |