From 9ee474f55664ff63111c843099d365e7ecffb56f Mon Sep 17 00:00:00 2001 From: Paul Turner Date: Thu, 4 Oct 2012 13:18:30 +0200 Subject: sched: Maintain the load contribution of blocked entities We are currently maintaining: runnable_load(cfs_rq) = \Sum task_load(t) For all running children t of cfs_rq. While this can be naturally updated for tasks in a runnable state (as they are scheduled); this does not account for the load contributed by blocked task entities. This can be solved by introducing a separate accounting for blocked load: blocked_load(cfs_rq) = \Sum runnable(b) * weight(b) Obviously we do not want to iterate over all blocked entities to account for their decay, we instead observe that: runnable_load(t) = \Sum p_i*y^i and that to account for an additional idle period we only need to compute: y*runnable_load(t). This means that we can compute all blocked entities at once by evaluating: blocked_load(cfs_rq)` = y * blocked_load(cfs_rq) Finally we maintain a decay counter so that when a sleeping entity re-awakens we can determine how much of its load should be removed from the blocked sum. Signed-off-by: Paul Turner Reviewed-by: Ben Segall Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20120823141506.585389902@google.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 81d8b1ba4100..b1831accfd89 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1103,6 +1103,7 @@ struct sched_avg { */ u32 runnable_avg_sum, runnable_avg_period; u64 last_runnable_update; + s64 decay_count; unsigned long load_avg_contrib; }; -- cgit v1.2.3