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authorVenkatesh Pallipadi <venki@google.com>2010-10-05 04:03:20 +0400
committerIngo Molnar <mingo@elte.hu>2010-10-18 22:52:25 +0400
commite82b8e4ea4f3dffe6e7939f90e78da675fcc450e (patch)
tree116e54691f87d2cb0f2f5df36d1e114624c225d0 /arch
parentb52bfee445d315549d41eacf2fa7c156e7d153d5 (diff)
downloadlinux-e82b8e4ea4f3dffe6e7939f90e78da675fcc450e.tar.xz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig11
-rw-r--r--arch/x86/kernel/tsc.c8
2 files changed, 19 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
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;