Messages in this thread |  | | | From | Lin Ming <> | | Subject | [PATCH v2 0/2] fix "perf top" soft lockups under Xen | | Date | Sat, 21 Apr 2012 00:11:03 +0800 |
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v2: - fix compile issues if no CONFIG_SMP, Konrad Rzeszutek Wilk - move inc_irq_stat after irq_work_run
These 2 patches fixed the "perf top" soft lockups under Xen reported by Steven at: https://lkml.org/lkml/2012/2/9/506
Both Steven and I tested it and "perf top" works well now.
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 | 9 +++ arch/x86/xen/smp.c | 111 +++++++++++++++++++++++++++++++++++- arch/x86/xen/smp.h | 12 ++++ 4 files changed, 129 insertions(+), 4 deletions(-)
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