summaryrefslogtreecommitdiffstats
path: root/arch/x86
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2009-06-20 10:57:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-20 10:57:40 -0700
commit1eb51c33b21ffa3fceb634d1d6bcd6488c79bc26 (patch)
tree5360e0b439b35a97313ea8250209e7dacff8b9a6 /arch/x86
parentb0b7065b64fe517b4a50915a1555e8ee98890d64 (diff)
parent3104bf03a923c72043a9c5009d9cd56724304916 (diff)
downloadop-kernel-dev-1eb51c33b21ffa3fceb634d1d6bcd6488c79bc26.zip
op-kernel-dev-1eb51c33b21ffa3fceb634d1d6bcd6488c79bc26.tar.gz
Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Fix out of scope variable access in sched_slice() sched: Hide runqueues from direct refer at source code level sched: Remove unneeded __ref tag sched, x86: Fix cpufreq + sched_clock() TSC scaling
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/timer.h6
-rw-r--r--arch/x86/kernel/tsc.c8
2 files changed, 11 insertions, 3 deletions
diff --git a/arch/x86/include/asm/timer.h b/arch/x86/include/asm/timer.h
index bd37ed4..20ca9c4 100644
--- a/arch/x86/include/asm/timer.h
+++ b/arch/x86/include/asm/timer.h
@@ -45,12 +45,16 @@ extern int no_timer_check;
*/
DECLARE_PER_CPU(unsigned long, cyc2ns);
+DECLARE_PER_CPU(unsigned long long, cyc2ns_offset);
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
static inline unsigned long long __cycles_2_ns(unsigned long long cyc)
{
- return cyc * per_cpu(cyc2ns, smp_processor_id()) >> CYC2NS_SCALE_FACTOR;
+ int cpu = smp_processor_id();
+ unsigned long long ns = per_cpu(cyc2ns_offset, cpu);
+ ns += cyc * per_cpu(cyc2ns, cpu) >> CYC2NS_SCALE_FACTOR;
+ return ns;
}
static inline unsigned long long cycles_2_ns(unsigned long long cyc)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index b0597ad..6e1a368 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -590,22 +590,26 @@ EXPORT_SYMBOL(recalibrate_cpu_khz);
*/
DEFINE_PER_CPU(unsigned long, cyc2ns);
+DEFINE_PER_CPU(unsigned long long, cyc2ns_offset);
static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
{
- unsigned long long tsc_now, ns_now;
+ unsigned long long tsc_now, ns_now, *offset;
unsigned long flags, *scale;
local_irq_save(flags);
sched_clock_idle_sleep_event();
scale = &per_cpu(cyc2ns, cpu);
+ offset = &per_cpu(cyc2ns_offset, cpu);
rdtscll(tsc_now);
ns_now = __cycles_2_ns(tsc_now);
- if (cpu_khz)
+ if (cpu_khz) {
*scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz;
+ *offset = ns_now - (tsc_now * *scale >> CYC2NS_SCALE_FACTOR);
+ }
sched_clock_idle_wakeup_event(0);
local_irq_restore(flags);
OpenPOWER on IntegriCloud