perf_counter: x86: self-IPI for pending work

Implement set_perf_counter_pending() with a self-IPI so that it will
run ASAP in a usable context.

For now use a second IRQ vector, because the primary vector pokes
the apic in funny ways that seem to confuse things.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.724626696@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 9c2754302ecc..d465487da587 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -67,6 +67,10 @@ static int show_other_interrupts(struct seq_file *p, int prec)
         for_each_online_cpu(j)
                 seq_printf(p, "%10u ", irq_stats(j)->apic_perf_irqs);
         seq_printf(p, "  Performance counter interrupts\n");
+        seq_printf(p, "PND: ");
+        for_each_online_cpu(j)
+                seq_printf(p, "%10u ", irq_stats(j)->apic_pending_irqs);
+        seq_printf(p, "  Performance pending work\n");
 #endif
         if (generic_interrupt_extension) {
                 seq_printf(p, "PLT: ");
@@ -171,6 +175,7 @@ u64 arch_irq_stat_cpu(unsigned int cpu)
         sum += irq_stats(cpu)->apic_timer_irqs;
         sum += irq_stats(cpu)->irq_spurious_count;
         sum += irq_stats(cpu)->apic_perf_irqs;
+        sum += irq_stats(cpu)->apic_pending_irqs;
 #endif
         if (generic_interrupt_extension)
                 sum += irq_stats(cpu)->generic_irqs;