On 01/20/2014 11:57 AM, Peter Zijlstra wrote: > On Fri, Jan 17, 2014 at 04:12:08PM -0500, [email protected] wrote: >> diff --git a/include/linux/sched.h b/include/linux/sched.h >> index 0af6c1a..52de567 100644 >> --- a/include/linux/sched.h >> +++ b/include/linux/sched.h >> @@ -1471,6 +1471,8 @@ struct task_struct { >> int numa_preferred_nid; >> unsigned long numa_migrate_retry; >> u64 node_stamp; /* migration stamp */ >> + u64 last_task_numa_placement; >> + u64 last_sum_exec_runtime; >> struct callback_head numa_work; >> >> struct list_head numa_entry; > >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 8e0a53a..0d395a0 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -1422,11 +1422,41 @@ static void update_task_scan_period(struct >> task_struct *p, >> memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); >> } >> >> +/* >> + * Get the fraction of time the task has been running since the last >> + * NUMA placement cycle. The scheduler keeps similar statistics, but >> + * decays those on a 32ms period, which is orders of magnitude off >> + * from the dozens-of-seconds NUMA balancing period. Use the scheduler >> + * stats only if the task is so new there are no NUMA statistics yet. >> + */ >> +static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) >> +{ >> + u64 runtime, delta, now; >> + /* Use the start of this time slice to avoid calculations. */ >> + now = p->se.exec_start; >> + runtime = p->se.sum_exec_runtime; >> + >> + if (p->last_task_numa_placement) { >> + delta = runtime - p->last_sum_exec_runtime; >> + *period = now - p->last_task_numa_placement; >> + } else { >> + delta = p->se.avg.runnable_avg_sum; >> + *period = p->se.avg.runnable_avg_period; >> + } >> + >> + p->last_sum_exec_runtime = runtime; >> + p->last_task_numa_placement = now; >> + >> + return delta; >> +} > > Have you tried what happens if you use p->se.avg.runnable_avg_sum / > p->se.avg.runnable_avg_period instead? If that also works it avoids > growing the datastructures and keeping of yet another set of runtime > stats.
That is what I started out with, and the results were not as stable as with this calculation. Having said that, I did that before I came up with patch 7/7, so maybe the effect would no longer be as pronounced any more as it was before... I can send in a simplified version, if you prefer. -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
