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sched/clock, x86/perf: Fix "perf test tsc"

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People reported that commit:

  5680d8094f ("sched/clock: Provide better clock continuity")

broke "perf test tsc".

That commit added another offset to the reported clock value; so
take that into account when computing the provided offset values.

Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 5680d8094f ("sched/clock: Provide better clock continuity")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2017-03-17 12:48:18 +01:00
committed by Ingo Molnar
parent 71fdb70eb4
commit 698eff6355
5 changed files with 28 additions and 22 deletions
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22
kernel/sched/clock.c
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@@ -96,10 +96,10 @@ static DEFINE_STATIC_KEY_FALSE(__sched_clock_stable);
static int __sched_clock_stable_early = 1;
/*
* We want: ktime_get_ns() + gtod_offset == sched_clock() + raw_offset
* We want: ktime_get_ns() + __gtod_offset == sched_clock() + __sched_clock_offset
*/
static __read_mostly u64 raw_offset;
static __read_mostly u64 gtod_offset;
__read_mostly u64 __sched_clock_offset;
static __read_mostly u64 __gtod_offset;
struct sched_clock_data {
u64 tick_raw;
@@ -131,11 +131,11 @@ static void __set_sched_clock_stable(void)
/*
* Attempt to make the (initial) unstable->stable transition continuous.
*/
raw_offset = (scd->tick_gtod + gtod_offset) - (scd->tick_raw);
__sched_clock_offset = (scd->tick_gtod + __gtod_offset) - (scd->tick_raw);
printk(KERN_INFO "sched_clock: Marking stable (%lld, %lld)->(%lld, %lld)\n",
scd->tick_gtod, gtod_offset,
scd->tick_raw, raw_offset);
scd->tick_gtod, __gtod_offset,
scd->tick_raw, __sched_clock_offset);
static_branch_enable(&__sched_clock_stable);
tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE);
@@ -161,11 +161,11 @@ static void __clear_sched_clock_stable(void)
*
* Still do what we can.
*/
gtod_offset = (scd->tick_raw + raw_offset) - (scd->tick_gtod);
__gtod_offset = (scd->tick_raw + __sched_clock_offset) - (scd->tick_gtod);
printk(KERN_INFO "sched_clock: Marking unstable (%lld, %lld)<-(%lld, %lld)\n",
scd->tick_gtod, gtod_offset,
scd->tick_raw, raw_offset);
scd->tick_gtod, __gtod_offset,
scd->tick_raw, __sched_clock_offset);
tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE);
@@ -238,7 +238,7 @@ again:
* scd->tick_gtod + TICK_NSEC);
*/
clock = scd->tick_gtod + gtod_offset + delta;
clock = scd->tick_gtod + __gtod_offset + delta;
min_clock = wrap_max(scd->tick_gtod, old_clock);
max_clock = wrap_max(old_clock, scd->tick_gtod + TICK_NSEC);
@@ -324,7 +324,7 @@ u64 sched_clock_cpu(int cpu)
u64 clock;
if (sched_clock_stable())
return sched_clock() + raw_offset;
return sched_clock() + __sched_clock_offset;
if (unlikely(!sched_clock_running))
return 0ull;