| Message ID | 20220209084929.54331-2-adrian.hunter@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | perf intel-pt: Add perf event clocks to better support VM tracing | expand |
On Wed, Feb 09, 2022 at 10:49:19AM +0200, Adrian Hunter wrote: > native_perf_sched_clock_from_tsc() is used to produce a time value that can > be consistent with perf_clock(). Consequently, it should be adjusted by > __sched_clock_offset, the same as perf_clock() would be. > > Fixes: 698eff6355f735 ("sched/clock, x86/perf: Fix perf test tsc") > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > --- > arch/x86/kernel/tsc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > index a698196377be..c1c73fe324cd 100644 > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -242,7 +242,8 @@ u64 native_sched_clock(void) > */ > u64 native_sched_clock_from_tsc(u64 tsc) > { > - return cycles_2_ns(tsc); > + return cycles_2_ns(tsc) + > + (sched_clock_stable() ? __sched_clock_offset : 0); > } Why do we care about the !sched_clock_stable() case?
On 09/02/2022 14:54, Peter Zijlstra wrote: > On Wed, Feb 09, 2022 at 10:49:19AM +0200, Adrian Hunter wrote: >> native_perf_sched_clock_from_tsc() is used to produce a time value that can >> be consistent with perf_clock(). Consequently, it should be adjusted by >> __sched_clock_offset, the same as perf_clock() would be. >> >> Fixes: 698eff6355f735 ("sched/clock, x86/perf: Fix perf test tsc") >> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> >> --- >> arch/x86/kernel/tsc.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c >> index a698196377be..c1c73fe324cd 100644 >> --- a/arch/x86/kernel/tsc.c >> +++ b/arch/x86/kernel/tsc.c >> @@ -242,7 +242,8 @@ u64 native_sched_clock(void) >> */ >> u64 native_sched_clock_from_tsc(u64 tsc) >> { >> - return cycles_2_ns(tsc); >> + return cycles_2_ns(tsc) + >> + (sched_clock_stable() ? __sched_clock_offset : 0); >> } > > Why do we care about the !sched_clock_stable() case? I guess we don't. So add __sched_clock_offset unconditionally then?
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index a698196377be..c1c73fe324cd 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -242,7 +242,8 @@ u64 native_sched_clock(void) */ u64 native_sched_clock_from_tsc(u64 tsc) { - return cycles_2_ns(tsc); + return cycles_2_ns(tsc) + + (sched_clock_stable() ? __sched_clock_offset : 0); } /* We need to define a real function for sched_clock, to override the
native_perf_sched_clock_from_tsc() is used to produce a time value that can be consistent with perf_clock(). Consequently, it should be adjusted by __sched_clock_offset, the same as perf_clock() would be. Fixes: 698eff6355f735 ("sched/clock, x86/perf: Fix perf test tsc") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> --- arch/x86/kernel/tsc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)