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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2007-08-25 18:41:53 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2007-08-25 18:41:53 +0200 |
| commit | 218050855ece4e923106ab614ac65afa0f618df3 (patch) | |
| tree | f7b1234ce9e8ad0bc5d5af949949251240ec6a2c /kernel/sched.c | |
| parent | 1fc84aaae3bae9646dd4c7798b8c0ff934338909 (diff) | |
| download | linux-stable-218050855ece4e923106ab614ac65afa0f618df3.tar.gz linux-stable-218050855ece4e923106ab614ac65afa0f618df3.tar.bz2 linux-stable-218050855ece4e923106ab614ac65afa0f618df3.zip | |
sched: adaptive scheduler granularity
Instead of specifying the preemption granularity, specify the wanted
latency. By fixing the granlarity to a constany the wakeup latency
it a function of the number of running tasks on the rq.
Invert this relation.
sysctl_sched_granularity becomes a minimum for the dynamic granularity
computed from the new sysctl_sched_latency.
Then use this latency to do more intelligent granularity decisions: if
there are fewer tasks running then we can schedule coarser. This helps
performance while still always keeping the latency target.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 6798328a2e0e..da26f46d50d7 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4911,14 +4911,18 @@ cpumask_t nohz_cpu_mask = CPU_MASK_NONE; static inline void sched_init_granularity(void) { unsigned int factor = 1 + ilog2(num_online_cpus()); - const unsigned long gran_limit = 100000000; + const unsigned long limit = 100000000; sysctl_sched_granularity *= factor; - if (sysctl_sched_granularity > gran_limit) - sysctl_sched_granularity = gran_limit; + if (sysctl_sched_granularity > limit) + sysctl_sched_granularity = limit; - sysctl_sched_runtime_limit = sysctl_sched_granularity * 5; - sysctl_sched_wakeup_granularity = sysctl_sched_granularity / 2; + sysctl_sched_latency *= factor; + if (sysctl_sched_latency > limit) + sysctl_sched_latency = limit; + + sysctl_sched_runtime_limit = sysctl_sched_latency * 5; + sysctl_sched_wakeup_granularity = sysctl_sched_latency / 2; } #ifdef CONFIG_SMP |