Messages in this thread | | | Subject | Re: perf sched record hangs machine | From | Peter Zijlstra <> | Date | Wed, 23 Sep 2009 10:52:48 +0200 |
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On Wed, 2009-09-23 at 12:48 +0400, Cyrill Gorcunov wrote: > On 9/23/09, Cyrill Gorcunov <gorcunov@gmail.com> wrote: > > On 9/23/09, Ingo Molnar <mingo@elte.hu> wrote: > >> > >> * Ingo Molnar <mingo@elte.hu> wrote: > >> > >>> > >>> * Peter Zijlstra <peterz@infradead.org> wrote: > >>> > >>> > .size default_send_IPI_self, .-default_send_IPI_self > >>> > > >>> > Which seems to suggest that cmove is in __prepare_ICR, but I'm not > >>> > sure how that can cause a page-fault, as that function is rather > >>> > pointer-less. > >>> > > >>> > Did it maybe delay evaluating apic->dest_logical that late, it appear > >>> > to be the first usage of that argument? > >>> > > >>> > Ingo, any ideas? > >>> > >>> Yeah, the problem is: > >>> > >>> [ 0.042445] Local APIC not detected. Using dummy APIC emulation. > >>> > >>> we shouldnt be trying to program the lapic in that case - all ops > >>> should be a NOP, including send-ipi-self. Cyrill? > >> > >> Cyrill, the right fix would be to define a: > >> > >> struct apic apic_none; > >> > >> with dummy functions injected. Set struct apic *apic to _that_, instead > >> of apic_default. > >> > >> This means that if we manage to detect a local APIC, we will set it to > >> apic_default (or some other driver) - but the bootup default will be 'no > >> APIC'. > >> > > > > May it wait till evening (i'll back from office and take a look)? > > > >> This is a lot cleaner and a lot less error-prone than the direct > >> frobbing of the function pointers. > >> > >> Ingo > >> > > > > Btw, meanwhile Chris may try to pass lapic boot-option in attempt to > reenable apic via msr registers. Also (iirc) i feel we may be hiding > errors if complete noop apic would be used since i belive we need to > check out under which condition a particular operation is called and > when apic is disabled it's mean we're switched to UP mode and > inter-cpu interrupts are under suspicion too. Will take a look during > ~6 hours ;)
Thing is, this is a self-ipi, nothing inter-cpu about it.
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