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, 8 insertions, 0 deletions

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 26a863a9c2a8..a1c2cd768538 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -104,10 +104,14 @@ int __init notsc_setup(char *str)
 
 __setup("notsc", notsc_setup);
 
+static int no_sched_irq_time;
+
 static int __init tsc_setup(char *str)
 {
         if (!strcmp(str, "reliable"))
                 tsc_clocksource_reliable = 1;
+        if (!strncmp(str, "noirqtime", 9))
+                no_sched_irq_time = 1;
         return 1;
 }
 
@@ -801,6 +805,7 @@ void mark_tsc_unstable(char *reason)
         if (!tsc_unstable) {
                 tsc_unstable = 1;
                 sched_clock_stable = 0;
+                disable_sched_clock_irqtime();
                 printk(KERN_INFO "Marking TSC unstable due to %s\n", reason);
                 /* Change only the rating, when not registered */
                 if (clocksource_tsc.mult)
@@ -987,6 +992,9 @@ void __init tsc_init(void)
         /* now allow native_sched_clock() to use rdtsc */
         tsc_disabled = 0;
 
+        if (!no_sched_irq_time)
+                enable_sched_clock_irqtime();
+
         lpj = ((u64)tsc_khz * 1000);
         do_div(lpj, HZ);
         lpj_fine = lpj;