Messages in this thread | | | Date | Fri, 24 Jul 2020 09:16:48 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR |
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On Thu, Jul 23, 2020 at 08:47:59PM +0200, peterz@infradead.org wrote: > On Thu, Jul 23, 2020 at 02:32:36PM -0400, Waiman Long wrote: > > BTW, do you have any comment on my v2 lock holder cpu info qspinlock patch? > > I will have to update the patch to fix the reported 0-day test problem, but > > I want to collect other feedback before sending out v3. > > I want to say I hate it all, it adds instructions to a path we spend an > aweful lot of time optimizing without really getting anything back for > it. > > Will, how do you feel about it?
I can see it potentially being useful for debugging, but I hate the limitation to 256 CPUs. Even arm64 is hitting that now.
Also, you're talking ~1% gains here. I think our collective time would be better spent off reviewing the CNA series and trying to make it more deterministic.
Will
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