Messages in this thread Patch in this message | | | Date | Tue, 07 May 2013 13:12:02 +0800 | From | Alex Shi <> | Subject | Re: [PATCH v5 5/7] sched: compute runnable load avg in cpu_load and cpu_avg_load_per_task |
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On 05/07/2013 02:34 AM, Paul Turner wrote: >> > Current load balance doesn't consider slept task's load which is >> > represented by blocked_load_avg. And the slept task is not on_rq, so >> > consider it in load balance is a little strange. > The load-balancer has a longer time horizon; think of blocked_loag_avg > to be a signal for the load, already assigned to this cpu, which is > expected to appear (within roughly the next quantum). > > Consider the following scenario: > > tasks: A,B (40% busy), C (90% busy) > > Suppose we have: > CPU 0: CPU 1: > A C > B > > Then, when C blocks the load balancer ticks. > > If we considered only runnable_load then A or B would be eligible for > migration to CPU 1, which is essentially where we are today. >
here is the changed patch according to Paul's comments. Is that you liked, Paul? :)
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From 1d7290530e2ee402874bbce39297bb1cfd882339 Mon Sep 17 00:00:00 2001 From: Alex Shi <alex.shi@intel.com> Date: Sat, 17 Nov 2012 13:56:11 +0800 Subject: [PATCH 5/7] sched: compute runnable load avg in cpu_load and cpu_avg_load_per_task
They are the base values in load balance, update them with rq runnable load average, then the load balance will consider runnable load avg naturally.
Signed-off-by: Alex Shi <alex.shi@intel.com> --- kernel/sched/core.c | 16 ++++++++++++++-- kernel/sched/fair.c | 8 ++++++-- 2 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 33d9a858..f4c6cac 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2536,9 +2536,14 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, void update_idle_cpu_load(struct rq *this_rq) { unsigned long curr_jiffies = ACCESS_ONCE(jiffies); - unsigned long load = this_rq->load.weight; + unsigned long load; unsigned long pending_updates; +#ifdef CONFIG_SMP + load = this_rq->cfs.runnable_load_avg + this_rq->cfs.blocked_load_avg; +#else + load = this_rq->load.weight; +#endif /* * bail if there's load or we're actually up-to-date. */ @@ -2582,11 +2587,18 @@ void update_cpu_load_nohz(void) */ static void update_cpu_load_active(struct rq *this_rq) { + unsigned long load; + +#ifdef CONFIG_SMP + load = this_rq->cfs.runnable_load_avg + this_rq->cfs.blocked_load_avg; +#else + load = this_rq->load.weight; +#endif /* * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). */ this_rq->last_load_update_tick = jiffies; - __update_cpu_load(this_rq, this_rq->load.weight, 1); + __update_cpu_load(this_rq, load, 1); calc_load_account_active(this_rq); } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2881d42..407ef61 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2900,7 +2900,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) /* Used instead of source_load when we know the type == 0 */ static unsigned long weighted_cpuload(const int cpu) { - return cpu_rq(cpu)->load.weight; + struct rq *rq = cpu_rq(cpu); + return rq->cfs.runnable_load_avg + rq->cfs.blocked_load_avg; } /* @@ -2946,8 +2947,11 @@ static unsigned long cpu_avg_load_per_task(int cpu) struct rq *rq = cpu_rq(cpu); unsigned long nr_running = ACCESS_ONCE(rq->nr_running); + unsigned long load_avg; + load_avg = rq->cfs.runnable_load_avg + rq->cfs.blocked_load_avg; + if (nr_running) - return rq->load.weight / nr_running; + return load_avg / nr_running; return 0; } -- 1.7.12
-- Thanks Alex
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