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Date: Wed, 23 Sep 2009 13:48:51 +0400 From: Cyrill Gorcunov <gorcunov@...il.com> To: Ingo Molnar <mingo@...e.hu> Cc: Chris Malley <mail@...ismalley.co.uk>, Peter Zijlstra <peterz@...radead.org>, Frederic Weisbecker <fweisbec@...il.com>, linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org> Subject: Re: perf sched record hangs machine On 9/23/09, Ingo Molnar <mingo@...e.hu> wrote: > > * Chris Malley <mail@...ismalley.co.uk> wrote: > >> 2009/9/23 Cyrill Gorcunov <gorcunov@...il.com>: >> > >> > 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 ;) >> > >> >> Hi Cyrill >> >> Heh, yes that just occurred to me as well. With the lapic boot option >> I can't reproduce the problem, and get a good recording every time. >> Don't know why the BIOS had disabled it (can't see any specific >> option). > > Would still be important to fix the crash - there are boxes where lapics > are disabled permanently and cannot be re-enabled. (plus most people > dont touch their defaults and dont add funky boot options - so crashing > is not an option) > Ingo, Chris, could you try Peter's patch? It seems like what we need. (Peter, self-ipi shouldn't be separated from others ipi, yes it may not issue any cycle on fsb, but iirc it uses the same logic as other ipi use) > I have such a test-box: > > [ 0.000000] Using APIC driver default > [ 0.000000] ACPI: PM-Timer IO Port: 0x8008 > [ 0.000000] SMP: Allowing 1 CPUs, 0 hotplug CPUs > [ 0.000000] Local APIC disabled by BIOS -- reenabling. > [ 0.000000] Could not enable APIC! > [ 0.000000] APIC: disable apic facility > > Btw., perf events can work even without a lapic (albeit without NMI > driven sampling): > > [ 0.052051] Performance Events: > [ 0.055138] no APIC, boot with the "lapic" boot parameter to force-enable > it. > [ 0.056014] no hardware sampling interrupt available. > [ 0.060014] p6 PMU driver. > [ 0.062955] ... version: 0 > [ 0.064014] ... bit width: 32 > [ 0.068014] ... generic registers: 2 > [ 0.072015] ... value mask: 00000000ffffffff > [ 0.076014] ... max period: 000000007fffffff > [ 0.080014] ... fixed-purpose events: 0 > [ 0.084014] ... event mask: 0000000000000003 > > That's what it did on your box too: > > [ 0.013679] Performance Events: > [ 0.013705] no APIC, boot with the "lapic" boot parameter to force-enable > it. > [ 0.013783] no hardware sampling interrupt available. > [ 0.013826] p6 PMU driver. > [ 0.013882] ... version: 0 > [ 0.013922] ... bit width: 32 > [ 0.013962] ... generic registers: 2 > [ 0.014002] ... value mask: 00000000ffffffff > [ 0.014045] ... max period: 000000007fffffff > [ 0.014088] ... fixed-purpose events: 0 > [ 0.014128] ... event mask: 0000000000000003 > > Unfortunately i cannot reproduce the crash you've been seeing. (but i'm > quite sure it's due to self-IPI not working fine with dummy lapic.) > > Ingo > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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