The patch titled
sched: improve sched_clock() on i686
has been added to the -mm tree. Its filename is
sched-improve-sched_clock-on-i686.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: sched: improve sched_clock() on i686
From: Ingo Molnar <mingo@xxxxxxx>
Clean up sched_clock() on i686: it will use the TSC if available and falls
back to jiffies only if the user asked for it to be disabled via notsc or
the CPU calibration code didnt figure out the right cpu_khz.
This generally makes the scheduler timestamps more finegrained, on all
hardware. (the current scheduler is pretty resistant against asynchronous
sched_clock() values on different CPUs, it will allow at most up to a jiffy
of jitter.)
Also simplify sched_clock()'s check for TSC availability: propagate the
desire and ability to use the TSC into the tsc_disable flag, previously
this flag only indicated whether the notsc option was passed. This makes
the rare low-res sched_clock() codepath a single branch off a read-mostly
flag.
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/tsc.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff -puN arch/i386/kernel/tsc.c~sched-improve-sched_clock-on-i686 arch/i386/kernel/tsc.c
--- a/arch/i386/kernel/tsc.c~sched-improve-sched_clock-on-i686
+++ a/arch/i386/kernel/tsc.c
@@ -112,13 +112,10 @@ unsigned long long sched_clock(void)
return (*custom_sched_clock)();
/*
- * in the NUMA case we dont use the TSC as they are not
- * synchronized across all CPUs.
+ * Fall back to jiffies if there's no TSC available:
*/
-#ifndef CONFIG_NUMA
- if (!cpu_khz || check_tsc_unstable())
-#endif
- /* no locking but a rare wrong value is not a big deal */
+ if (unlikely(tsc_disable))
+ /* No locking but a rare wrong value is not a big deal: */
return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
/* read the Time Stamp Counter: */
@@ -198,13 +195,13 @@ EXPORT_SYMBOL(recalibrate_cpu_khz);
void __init tsc_init(void)
{
if (!cpu_has_tsc || tsc_disable)
- return;
+ goto out_no_tsc;
cpu_khz = calculate_cpu_khz();
tsc_khz = cpu_khz;
if (!cpu_khz)
- return;
+ goto out_no_tsc;
printk("Detected %lu.%03lu MHz processor.\n",
(unsigned long)cpu_khz / 1000,
@@ -212,6 +209,15 @@ void __init tsc_init(void)
set_cyc2ns_scale(cpu_khz);
use_tsc_delay();
+ return;
+
+out_no_tsc:
+ /*
+ * Set the tsc_disable flag if there's no TSC support, this
+ * makes it a fast flag for the kernel to see whether it
+ * should be using the TSC.
+ */
+ tsc_disable = 1;
}
#ifdef CONFIG_CPU_FREQ
_
Patches currently in -mm which might be from mingo@xxxxxxx are
change-warn_on-back-to-bug-at.patch
rcu-rcutorture-suspend-fix.patch
acpi-i686-x86_64-fix-laptop-bootup-hang-in-init_acpi.patch
revert-i386-fix-the-verify_quirk_intel_irqbalance.patch
revert-x86_64-mm-add-genapic_force.patch
revert-x86_64-mm-fix-the-irqbalance-quirk-for-e7320-e7520-e7525.patch
convert-i386-pda-code-to-use-%fs.patch
genapic-optimize-fix-apic-mode-setup-2.patch
genapic-always-use-physical-delivery-mode-on-8-cpus.patch
genapic-remove-es7000-workaround.patch
genapic-remove-clustered-apic-mode.patch
genapic-default-to-physical-mode-on-hotplug-cpu-kernels.patch
x86_64-do-not-enable-the-nmi-watchdog-by-default.patch
sched-improve-sched_clock-on-i686.patch
sched-improve-sched_clock-on-i686-fix.patch
cpuset-remove-sched-domain-hooks-from-cpusets.patch
schedule_on_each_cpu-use-preempt_disable.patch
lockdep-also-check-for-freed-locks-in-kmem_cache_free.patch
lockdep-more-unlock-on-error-fixes.patch
lockdep-more-unlock-on-error-fixes-fix.patch
lockdep-add-graph-depth-information-to-proc-lockdep.patch
gtod-uninline-jiffiesh.patch
gtod-fix-multiple-conversion-bugs-in-msecs_to_jiffies.patch
gtod-fix-timeout-overflow.patch
gtod-persistent-clock-support-core.patch
gtod-persistent-clock-support-i386.patch
dynticks-uninline-irq_enter.patch
dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie.patch
hrtimers-namespace-and-enum-cleanup.patch
hrtimers-clean-up-locking.patch
hrtimers-add-state-tracking.patch
hrtimers-clean-up-callback-tracking.patch
hrtimers-move-and-add-documentation.patch
acpi-include-fix.patch
acpi-keep-track-of-timer-broadcast.patch
acpi-add-state-propagation-for-dynamic-broadcasting.patch
acpi-cleanups-allow-early-access-to-pmtimer.patch
i386-apic-clean-up-the-apic-code.patch
clockevents-core.patch
clockevents-i386-drivers.patch
clockevents-i386-drivers-high-res-timers-fix-apic-event-broadcasting-code.patch
clockevents-i386-hpet-driver.patch
i386-apic-rework-and-fix-local-apic-calibration.patch
high-res-timers-core.patch
high-res-timers-core-do-itimer-rearming-in-process-context.patch
high-res-timers-core-do-itimer-rearming-in-process-context-fix2.patch
high-res-timers-core-hrtimers-add-state-tracking-fix.patch
high-res-timers-core-hrtimers-add-state-tracking-fix-fix.patch
high-res-timers-allow-tsc-clocksource-if-pmtimer-present.patch
dynticks-core.patch
dynticks-add-nohz-stats-to-proc-stat.patch
dynticks-i386-support-idle-handler-callbacks.patch
dynticks-i386-prepare-nmi-watchdog.patch
high-res-timers-dynticks-i386-support-enable-in-kconfig.patch
debugging-feature-add-proc-timer_stat.patch
debugging-feature-proc-timer_list.patch
debugging-feature-sysrq-q-to-print-timers.patch
generic-vsyscall-gtod-support-for-generic_time.patch
generic-vsyscall-gtod-support-for-generic_time-tidy.patch
time-x86_64-hpet_address-cleanup.patch
time-x86_64-split-x86_64-kernel-timec-up.patch
time-x86_64-split-x86_64-kernel-timec-up-tidy.patch
time-x86_64-convert-x86_64-to-use-generic_time.patch
time-x86_64-convert-x86_64-to-use-generic_time-tidy.patch
time-x86_64-re-enable-vsyscall-support-for-x86_64.patch
time-x86_64-re-enable-vsyscall-support-for-x86_64-tidy.patch
workqueue-dont-hold-workqueue_mutex-in-flush_scheduled_work.patch
mm-only-sched-add-a-few-scheduler-event-counters.patch
sched-add-above-background-load-function.patch
mm-implement-swap-prefetching.patch
mm-implement-swap-prefetching-use-ctl_unnumbered.patch
sched-cleanup-remove-task_t-convert-to-struct-task_struct-prefetch.patch
detect-atomic-counter-underflows.patch
debug-shared-irqs.patch
make-frame_pointer-default=y.patch
mutex-subsystem-synchro-test-module.patch
vdso-print-fatal-signals.patch
vdso-improve-print_fatal_signals-support-by-adding-memory-maps.patch
vdso-print-fatal-signals-use-ctl_unnumbered.patch
lockdep-show-held-locks-when-showing-a-stackdump.patch
lockdep-show-held-locks-when-showing-a-stackdump-fix.patch
lockdep-show-held-locks-when-showing-a-stackdump-fix-2.patch
kmap_atomic-debugging.patch
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