Messages in this thread | | | Subject | Re: [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers | From | Mike Galbraith <> | Date | Tue, 26 Oct 2021 12:15:31 +0200 |
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On Tue, 2021-10-26 at 09:18 +0100, Mel Gorman wrote: > On Mon, Oct 25, 2021 at 08:35:52AM +0200, Mike Galbraith wrote: > > > > > My desktop trace session said distribution improved a bit, but there > > was no meaningful latency or throughput improvement, making for a > > pretty clear "nope" to the above question. > > Another interpretation is that it's simply neutral and does no harm.
Yes, patchlet not completely countermanding PELT is a good sign. Had it continuously fired and countermanded PELT entirely, that would mean either that it was busted, or that the desktop load is so damn over- threaded as to be continuously waking more damn threads than can possibly have any benefit whatsoever. Neither of those having happened happening is a good thing. While I really dislike PELT's evil side, it's other face is rather attractive... rob
> > It benefiting NUMA box > > hackbench is a valid indicator, but one that is IMO too disconnected > > from the real world to carry much weight. > > > > I think if it's not shown to be harmful to a realistic workload but helps > an overloaded example then it should be ok. While excessive overload is > rare in a realistic workload, it does happen. There are a few workloads > I've seen bugs for that were triggered when an excessive number of worker > threads get spawned and compete for CPU access which in turns leads more > worker threads get spawned. There are application workarounds for this > corner case but it still triggers bugs. >
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