The following commit has been merged in the linux branch: commit e7ab0f7b50bc4688fb5cf65de5d42e3b882fb8d1 Author: Ingo Molnar mingo@elte.hu Date: Fri Oct 9 15:58:20 2009 +0200

Revert "x86, timers: Check for pending timers after (device) interrupts"

This reverts commit 9bcbdd9c58617f1301dd4f17c738bb9bc73aca70.

The real bug producing LatencyTop latencies has been fixed in:

f5dc375: sched: Update the clock of runqueue select_task_rq() selected

And the commit being reverted here triggers local timer processing from every device IRQ. If device IRQs come in at a high frequency, this could cause a performance regression.

The commit being reverted here purely 'fixed' the reported latency as a side effect, because CPUs were being moved out of idle more often.

Acked-by: Peter Zijlstra peterz@infradead.org Cc: Arjan van de Ven arjan@linux.intel.com Cc: Frans Pop elendil@planet.nl Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Mike Galbraith efault@gmx.de Cc: Thomas Gleixner tglx@linutronix.de LKML-Reference: 20091008064041.67219b13@infradead.org Signed-off-by: Ingo Molnar mingo@elte.hu

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 3912061..74656d1 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -244,7 +244,6 @@ unsigned int __irq_entry do_IRQ(struct pt_regs *regs) __func__, smp_processor_id(), vector, irq); }

- run_local_timers(); irq_exit();

set_irq_regs(old_regs); @@ -269,7 +268,6 @@ void smp_generic_interrupt(struct pt_regs *regs) if (generic_interrupt_extension) generic_interrupt_extension();

- run_local_timers(); irq_exit();

set_irq_regs(old_regs); diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index d915d95..ec1de97 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -198,7 +198,6 @@ void smp_reschedule_interrupt(struct pt_regs *regs) { ack_APIC_irq(); inc_irq_stat(irq_resched_count); - run_local_timers(); /* * KVM uses this interrupt to force a cpu out of guest mode */