Messages in this thread | | | Date | Thu, 27 Nov 2014 17:17:38 +0800 | From | Wanpeng Li <> | Subject | Re: [PATCH] sched/rt: don't try to balance rt_runtime when it is futile |
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Hi Mike, On 5/15/14, 10:49 AM, Mike Galbraith wrote: > On Wed, 2014-05-14 at 15:11 -0400, Paul Gortmaker wrote: > >> Given that, perhaps a separate change to sched_rt_runtime_exceeded() >> that works out the CPU from the rt_rq, and returns zero if it is a >> nohz_full cpu? Does that make sense? Then the nohz_full people won't >> get the throttling message even if they go 100%. > I don't get it. What reason would there be to run a hog on a dedicated > core as realtime policy/priority? Given no competition, there's nothing > to prioritize, you could just as well run a critical task as SCHED_IDLE. > > I would also expect that anyone wanting bare metal will have all of > their critical cores isolated from the scheduler, watchdogs turned off > as well as that noisy throttle, the whole point being to make as much > silent as possible. Seems to me tick_nohz_full_cpu(cpu) should be > predicated by that cpu being isolated from the #1 noise source, the > scheduler and its load balancing. There's just no point to nohz_full > without that, or if there is, I sure don't see it.
If the tick is still need to be handled if cpu is isolated w/o nohz full enabled?
Regards, Wanpeng Li
> > When I see people trying to run a hog as a realtime task, it's because > they are trying in vain to keep competition away from precious cores.. > and one mlockall with a realtime hog blocking flush_work() gives them a > wakeup call. > > -Mike > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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