Thanks, Peter. On Mon, Jul 07, 2014 at 12:46:46PM +0200, Peter Zijlstra wrote: > > That tg->load_avg cacheline is already red hot glowing, and you've just > increased the amount of updates to it.. That's not going to be pleasant. >
Logically, this rewrite updates tg->load_avg as soon as it is changed. But technically, this is not necessary, as it is only needed to be updated when it is used before update_cfs_shares() and update_cfs_rq_h_load(). Yes, I can optimize it. > So here you add the task to the cfs_rq avg when its got migrate in, > however: > > > @@ -4552,17 +4326,9 @@ migrate_task_rq_fair(struct task_struct *p, int > > next_cpu) > > struct sched_entity *se = &p->se; > > struct cfs_rq *cfs_rq = cfs_rq_of(se); > > > > + /* Update task on old CPU, then ready to go (entity must be off the > > queue) */ > > + __update_load_avg(cfs_rq_clock_task(cfs_rq), &se->avg, 0); > > + se->avg.last_update_time = 0; > > > > /* We have migrated, no longer consider this task hot */ > > se->exec_start = 0; > > there you don't remove it first.. > Yes, I missed it. I wonder what I was thinking. Migration is the only reason to track task load average... Yuyang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
