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authorDan Williams <dan.j.williams@intel.com>2009-09-08 17:55:21 -0700
committerDan Williams <dan.j.williams@intel.com>2009-09-08 17:55:21 -0700
commitbbb20089a3275a19e475dbc21320c3742e3ca423 (patch)
tree216fdc1cbef450ca688135c5b8969169482d9a48 /arch/x86/kernel/tsc.c
parent3e48e656903e9fd8bc805c6a2c4264d7808d315b (diff)
parent657a77fa7284d8ae28dfa48f1dc5d919bf5b2843 (diff)
Merge branch 'dmaengine' into async-tx-next
Conflicts: crypto/async_tx/async_xor.c drivers/dma/ioat/dma_v2.h drivers/dma/ioat/pci.c drivers/md/raid5.c
Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c36
1 files changed, 24 insertions, 12 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index d57de05dc43..6e1a368d21d 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -9,6 +9,7 @@
#include <linux/delay.h>
#include <linux/clocksource.h>
#include <linux/percpu.h>
+#include <linux/timex.h>
#include <asm/hpet.h>
#include <asm/timer.h>
@@ -384,13 +385,13 @@ unsigned long native_calibrate_tsc(void)
{
u64 tsc1, tsc2, delta, ref1, ref2;
unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX;
- unsigned long flags, latch, ms, fast_calibrate, tsc_khz;
+ unsigned long flags, latch, ms, fast_calibrate, hv_tsc_khz;
int hpet = is_hpet_enabled(), i, loopmin;
- tsc_khz = get_hypervisor_tsc_freq();
- if (tsc_khz) {
+ hv_tsc_khz = get_hypervisor_tsc_freq();
+ if (hv_tsc_khz) {
printk(KERN_INFO "TSC: Frequency read from the hypervisor\n");
- return tsc_khz;
+ return hv_tsc_khz;
}
local_irq_save(flags);
@@ -589,22 +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);
@@ -631,17 +636,15 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
struct cpufreq_freqs *freq = data;
- unsigned long *lpj, dummy;
+ unsigned long *lpj;
if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
return 0;
- lpj = &dummy;
- if (!(freq->flags & CPUFREQ_CONST_LOOPS))
+ lpj = &boot_cpu_data.loops_per_jiffy;
#ifdef CONFIG_SMP
+ if (!(freq->flags & CPUFREQ_CONST_LOOPS))
lpj = &cpu_data(freq->cpu).loops_per_jiffy;
-#else
- lpj = &boot_cpu_data.loops_per_jiffy;
#endif
if (!ref_freq) {
@@ -710,7 +713,16 @@ static cycle_t read_tsc(struct clocksource *cs)
#ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_tsc(void)
{
- cycle_t ret = (cycle_t)vget_cycles();
+ cycle_t ret;
+
+ /*
+ * Surround the RDTSC by barriers, to make sure it's not
+ * speculated to outside the seqlock critical section and
+ * does not cause time warps:
+ */
+ rdtsc_barrier();
+ ret = (cycle_t)vget_cycles();
+ rdtsc_barrier();
return ret >= __vsyscall_gtod_data.clock.cycle_last ?
ret : __vsyscall_gtod_data.clock.cycle_last;