Messages in this thread | | | Subject | Re: [RFC][PATCH] sched/rt: Use IPI to trigger RT task push migration instead of pulling | From | Mike Galbraith <> | Date | Fri, 06 Feb 2015 16:58:08 +0100 |
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On Fri, 2015-02-06 at 13:40 +0100, Peter Zijlstra wrote: > On Thu, Feb 05, 2015 at 11:04:20AM -0500, Steven Rostedt wrote:
> Well, the thing is, with or without this patch, the worst case is still > the very same. The likelihood of actually triggering it goes down > dramatically [*], but any spin_lock() has that O(nr_cpus) worst case, and > that spinlock op isn't going away. > > Now, lowering avg/median cases is good, but don't kid yourself that the > worst case is going to be better. > > People running -RT on big boxes had better be aware of this.
The folks I know of running -RT on big boxen isolate cores and nail absolutely everything to the floor. The only way to survive in a big box is to chop the thing into tiny pieces. A plasma cutter would be even better.. 'course you could just _buy smaller boxen_ and connect what you want connected, take the lazy path to big box solution ;-)
-Mike
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