diff options
| author | Paul Turner <pjt@google.com> | 2012-10-04 13:18:29 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-10-24 10:27:18 +0200 |
| commit | 9d85f21c94f7f7a84d0ba686c58aa6d9da58fdbb (patch) | |
| tree | bec53516fbe39007b12250423b7a09e7b62184c3 /kernel/sched/core.c | |
| parent | 0e9e3e306c7e472bdcffa34c4c4584301eda03b3 (diff) | |
sched: Track the runnable average on a per-task entity basis
Instead of tracking averaging the load parented by a cfs_rq, we can track
entity load directly. With the load for a given cfs_rq then being the sum
of its children.
To do this we represent the historical contribution to runnable average
within each trailing 1024us of execution as the coefficients of a
geometric series.
We can express this for a given task t as:
runnable_sum(t) = \Sum u_i * y^i, runnable_avg_period(t) = \Sum 1024 * y^i
load(t) = weight_t * runnable_sum(t) / runnable_avg_period(t)
Where: u_i is the usage in the last i`th 1024us period (approximately 1ms)
~ms and y is chosen such that y^k = 1/2. We currently choose k to be 32 which
roughly translates to about a sched period.
Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.372695337@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2d8927fda71..fd9d0859350 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1524,6 +1524,11 @@ static void __sched_fork(struct task_struct *p) p->se.vruntime = 0; INIT_LIST_HEAD(&p->se.group_node); +#ifdef CONFIG_SMP + p->se.avg.runnable_avg_period = 0; + p->se.avg.runnable_avg_sum = 0; +#endif + #ifdef CONFIG_SCHEDSTATS memset(&p->se.statistics, 0, sizeof(p->se.statistics)); #endif |