lkml.org 
[lkml]   [2012]   [Apr]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject
Date
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



\
 
 \ /
  Last update: 2012-04-15 08:11    [from the cache]
©2003-2011 Jasper Spaans