Messages in this thread | | | Date | Mon, 20 Jul 2015 17:27:44 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/smpboot: Check for cpu_active on cpu initialization |
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On Mon, Jul 20, 2015 at 05:18:31PM +0200, Joerg Roedel wrote: > On Mon, Jul 20, 2015 at 05:10:00PM +0200, Borislav Petkov wrote: > > On Mon, Jul 20, 2015 at 05:02:40PM +0200, Joerg Roedel wrote: > > > I have seen a report where this happens on bare metal, when the change > > > to the cpu_active bit becomes visible on the other CPU significantly > > > later than the the cpu_online bit. This happened on a pretty big machine > > > with 88 cores. > > > > So how about what I proposed at the end of my previous mail? > > Oh sorry, I missed that. Setting cpu_active first should work on x86, > where writes become visible in the order they are executed. But this > function is in generic code and I have no idea what this change might > break on other architectures. > > In the end cpu_active means that the scheduler can push tasks to the > CPU, no idea if some arch code breaks when the scheduler is already > working on a CPU before it becomes visibly online.
Hmm...
Let's run it by Peter.
@Peter: see the first patch in the mail for the problem of which cpumask bit to test wrt scheduler and migrating tasks to newly appearing cores...
Thanks.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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