Messages in this thread | | | Date | Thu, 21 Jun 2012 09:10:59 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [PATCH v3] sched: balance_cpu to consider other cpus in its group as target of (pinned) task |
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* Peter Zijlstra <peterz@infradead.org> [2012-06-20 19:38:21]:
> On Tue, 2012-06-19 at 17:43 +0530, Prashanth Nageshappa wrote: > > T2 will starve eternally in this case. The same > > scenario can arise in presence of non-rt tasks as well (say we replace F1 with > > high irq load or with a very high priority SCHED_OTHER task that can't move out > > of C2). > > Uhm, no. In the case where both F1 and T2 are SCHED_OTHER starvation is > impossible. > > What can happen with pure SCHED_OTHER affinities is being less fair than > desired.
Right ..sorry should have made that more explicit in the description.
> Anyway, I took the patch with a few minor edits
Thanks!
> -- ie. we don't need to > reset loop_break, its never changed (same for the ALL_PINNED patch you > sent).
Hmm ..I can see loop_break being incremented here:
/* take a breather every nr_migrate tasks */ if (env->loop > env->loop_break) { env->loop_break += sched_nr_migrate_break; env->flags |= LBF_NEED_BREAK; goto out; }
As a result, when we redo with a different src_cpu, both loop and loop_break could be at non-default values. Am I missing something here?
- vatsa
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