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 <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Frans Pop <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Thomas Gleixner <[email protected]>
LKML-Reference: <20091008064041.67219b13@infradead.org>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 391206199515651717fb88e8645c02e6ce482f21..74656d1d4e30f8fa560391253bb6b541b74e2b08 100644 (file)
--- 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 d915d956e66de6777450e2b6725a96799efe25c6..ec1de97600e70638bcfdcb53da52a83bc1288829 100644 (file)
--- 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
         */