Messages in this thread | | | Subject | Re: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR | From | Waiman Long <> | Date | Thu, 23 Jul 2020 15:04:13 -0400 |
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On 7/23/20 2:47 PM, 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.
It does add some extra instruction that may slow it down slightly, but I don't agree that it gives nothing back. The cpu lock holder information can be useful in analyzing crash dumps and in some debugging situation. I think it can be useful in RHEL for this readon. How about an x86 config option to allow distros to decide if they want to have it enabled? I will make sure that it will have no performance degradation if the option is not enabled.
Cheers, Longman
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