Messages in this thread | | | Date | Mon, 18 May 2015 19:59:40 +0530 | From | Srikar Dronamraju <> | Subject | Re: [RFC][PATCH 4/4] sched, numa: Ignore pinned tasks |
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* Peter Zijlstra <peterz@infradead.org> [2015-05-18 15:06:58]:
> On Mon, 2015-05-18 at 18:30 +0530, Srikar Dronamraju wrote: > > > > > > static void account_numa_dequeue(struct rq *rq, struct task_struct *p) > > > { > > > + if (p->nr_cpus_allowed == 1) { > > > + rq->nr_pinned_running--; > > > + WARN_ON_ONCE(p->numa_preferred_nid != -1); > > > + } > > > rq->nr_numa_running -= (p->numa_preferred_nid != -1); > > > rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); > > > } > > > > > > Shouldnt we reset p->numa_preferred_nid when we are setting the allowed > > cpus in set_cpus_allowed_common()? > > > > Otherwise if an process is set a preferred node based on its numa faults > > but then is pinned to a different cpu, then we can see this warning.:w! > > We should never get preferred_nid set when nr_cpus_allowed == 1, see the > hunk that changes task_tick_numa. > > So we set preferred = -1 on pinning, do not partake in numa balancing > while this is so, therefore it should still be so when we dequeue, > right?
lets say if a thread were to do a sched_setaffinity on itself ; would it not call account_numa_dequeue before account_numa_enqueue?
Also setting preferred = -1 in set_cpus_allowed avoids us from setting it at account_numa_enqueue. account_numa_enqueue() would probably be called more times than set_cpus_allowed.
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-- Thanks and Regards Srikar Dronamraju
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