Messages in this thread Patch in this message | | | Date | Sat, 05 Jan 2013 16:56:17 +0800 | From | Alex Shi <> | Subject | Re: [PATCH v3 09/22] sched: compute runnable load avg in cpu_load and cpu_avg_load_per_task |
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On 01/05/2013 04:37 PM, Alex Shi wrote: > 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 | 8 ++++++++ > kernel/sched/fair.c | 4 ++-- > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 06d27af..5feed5e 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2544,7 +2544,11 @@ 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); > +#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED) > + unsigned long load = (unsigned long)this_rq->cfs.runnable_load_avg; > +#else > unsigned long load = this_rq->load.weight; > +#endif > unsigned long pending_updates; > > /* > @@ -2594,7 +2598,11 @@ static void update_cpu_load_active(struct rq *this_rq) > * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). > */ > this_rq->last_load_update_tick = jiffies; > +#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED) > + __update_cpu_load(this_rq, this_rq->cfs.runnable_load_avg, 1); > +#else > __update_cpu_load(this_rq, this_rq->load.weight, 1); > +#endif > > calc_load_account_active(this_rq); > } > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 5c545e4..84a6517 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -2906,7 +2906,7 @@ 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; > + return (unsigned long)cpu_rq(cpu)->cfs.runnable_load_avg;
Above line change cause aim9 multitask benchmark drop about 10% performance on many x86 machines. Profile just show there are more cpuidle enter called. The testing command:
#( echo $hostname ; echo test ; echo 1 ; echo 2000 ; echo 2 ; echo 2000 ; echo 100 ) | ./multitask -nl
The oprofile output here: with this patch set 101978 total 0.0134 54406 cpuidle_wrap_enter 499.1376 2098 __do_page_fault 2.0349 1976 rwsem_wake 29.0588 1824 finish_task_switch 12.4932 1560 copy_user_generic_string 24.3750 1346 clear_page_c 84.1250 1249 unmap_single_vma 0.6885 1141 copy_page_rep 71.3125 1093 anon_vma_interval_tree_insert 8.1567
3.8-rc2 68982 total 0.0090 22166 cpuidle_wrap_enter 203.3578 2188 rwsem_wake 32.1765 2136 __do_page_fault 2.0718 1920 finish_task_switch 13.1507 1724 poll_idle 15.2566 1433 copy_user_generic_string 22.3906 1237 clear_page_c 77.3125 1222 unmap_single_vma 0.6736 1053 anon_vma_interval_tree_insert 7.8582
Without load avg in periodic balancing, each cpu will weighted with all tasks load.
with new load tracking, we just update the cfs_rq load avg with each task at enqueue/dequeue moment, and with just update current task in scheduler_tick. I am wondering if it's the sample is a bit rare.
What's your opinion of this, Paul?
> } > > /* > @@ -2953,7 +2953,7 @@ static unsigned long cpu_avg_load_per_task(int cpu) > unsigned long nr_running = ACCESS_ONCE(rq->nr_running); > > if (nr_running) > - return rq->load.weight / nr_running; > + return (unsigned long)rq->cfs.runnable_load_avg / nr_running; > > return 0; > } >
-- Thanks Alex
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