Messages in this thread | | | Date | Sun, 15 Apr 2012 14:14:57 +0800 | Subject | Re: [PATCH 0/2] fix "perf top" soft lockups under Xen | From | Lin Ming <> |
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(Forgot mail subject, add it)
On Sun, Apr 15, 2012 at 2:09 PM, Lin Ming <mlin@ss.pku.edu.cn> wrote: > Hi all, > > These 2 patches try to fix the "perf top" soft lockups under Xen > reported by Steven at: https://lkml.org/lkml/2012/2/9/506 > > I tested it with 3.4-rc2 and "perf top" works well now. > > Steven, > Could you please help to test it too? > > The soft lockup code path is: > > __irq_work_queue > arch_irq_work_raise > apic->send_IPI_self(IRQ_WORK_VECTOR); > apic_send_IPI_self > __default_send_IPI_shortcut > __xapic_wait_icr_idle > > static inline void __xapic_wait_icr_idle(void) > { > while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY) > cpu_relax(); > } > > The lockup happens at above while looop. > > The cause is that Xen has not implemented the APIC IPI interface yet. > Xen has IPI interface: xen_send_IPI_one, but it's only used in > xen_smp_send_reschedule, xen_smp_send_call_function_ipi and > xen_smp_send_call_function_single_ipi, etc. > > So we need to implement Xen's APIC IPI interface as Ben's patch does. > And implement Xen's IRQ_WORK_VECTOR handler. > > Ben Guthro (1): > xen: implement apic ipi interface > > Lin Ming (1): > xen: implement IRQ_WORK_VECTOR handler > > arch/x86/include/asm/xen/events.h | 1 + > arch/x86/xen/enlighten.c | 7 ++ > arch/x86/xen/smp.c | 111 +++++++++++++++++++++++++++++++++++- > arch/x86/xen/smp.h | 12 ++++ > 4 files changed, 127 insertions(+), 4 deletions(-) > > Any comment is appreciated. > Lin Ming -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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