[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Null scheduler and vwfi native problem
On Thu, 2021-01-21 at 19:40 +0000, Julien Grall wrote: > Hi Dario, > Hi! > On 21/01/2021 18:32, Dario Faggioli wrote: > > On Thu, 2021-01-21 at 11:54 +0100, Anders Törnqvist wrote: > > > > > > https://lists.xenproject.org/archives/html/xen-devel/2018-09/msg01213.html > > > . > > > > > Right. Back then, PCI passthrough was involved, if I remember > > correctly. Is it the case for you as well? > > PCI passthrough is not yet supported on Arm :). However, the bug was > reported with platform device passthrough. > Yeah, well... That! Which indeed is not PCI. Sorry for the terminology mismatch. :-) > > Well, I'll think about it. > > > > Starting the system without "sched=null vwfi=native" does not > > > result > > > in > > > the problem. > > > > > Ok, how about, if you're up for some more testing: > > > > - booting with "sched=null" but not with "vwfi=native" > > - booting with "sched=null vwfi=native" but not doing the IRQ > > passthrough that you mentioned above > > > > ? > > I think we can skip the testing as the bug was fully diagnostics back > then. Unfortunately, I don't think a patch was ever posted. > True. But an hackish debug patch was provided and, back then, it worked. OTOH, Anders seems to be reporting that such a patch did not work here. I also continue to think that we're facing the same or a very similar problem... But I'm curious why applying the patch did not help this time. And that's why I asked for more testing. Anyway, it's true that we left the issue pending, so something like this: > From Xen PoV, any pCPU executing guest context can be considered > quiescent. So one way to solve the problem would be to mark the pCPU > when entering to the guest. > Should be done anyway. We'll then see if it actually solves this problem too, or if this is really something else. Thanks for the summary, BTW. :-) I'll try to work on a patch. Regards > [1] > > https://lore.kernel.org/xen-devel/acbeae1c-fda1-a079-322a-786d7528ecfc@xxxxxxx/ -- Dario Faggioli, Ph.D http://about.me/dario.faggioli Virtualization Software Engineer SUSE Labs, SUSE https://www.suse.com/ ------------------------------------------------------------------- <<This happens because _I_ choose it to happen!>> (Raistlin Majere) Attachment:
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