x86: Add IRQ_TIME_ACCOUNTING

This patch adds IRQ_TIME_ACCOUNTING option on x86 and runtime enables it
when TSC is enabled.

This change just enables fine grained irq time accounting, isn't used yet.
Following patches use it for different purposes.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-6-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cea0cd9a316f..f4c70c246ffe 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -795,6 +795,17 @@ config SCHED_MC
           making when dealing with multi-core CPU chips at a cost of slightly
           increased overhead in some places. If unsure say N here.
 
+config IRQ_TIME_ACCOUNTING
+        bool "Fine granularity task level IRQ time accounting"
+        default n
+        ---help---
+          Select this option to enable fine granularity task irq time
+          accounting. This is done by reading a timestamp on each
+          transitions between softirq and hardirq state, so there can be a
+          small performance impact.
+
+          If in doubt, say N here.
+
 source "kernel/Kconfig.preempt"
 
 config X86_UP_APIC