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
