| Message ID | 20230710122138.1450930-5-james.clark@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability | expand |
On Mon, Jul 10, 2023 at 5:22 AM James Clark <james.clark@arm.com> wrote: > > Since commit bd2756811766 ("perf: Rewrite core context handling") the > relationship between perf_event_context and PMUs has changed so that > the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally > silenced no longer exists. > > Remove the capability to avoid confusion that it actually influences > any perf core behavior. This change should be a no-op. > > Signed-off-by: James Clark <james.clark@arm.com> Acked-by: Ian Rogers <irogers@google.com> Thanks, Ian > --- > include/linux/perf_event.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index d5628a7b5eaa..3f4d941fd6c5 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -288,7 +288,7 @@ struct perf_event_pmu_context; > #define PERF_PMU_CAP_EXTENDED_REGS 0x0008 > #define PERF_PMU_CAP_EXCLUSIVE 0x0010 > #define PERF_PMU_CAP_ITRACE 0x0020 > -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x0040 > +/* Unused 0x0040 */ > #define PERF_PMU_CAP_NO_EXCLUDE 0x0080 > #define PERF_PMU_CAP_AUX_OUTPUT 0x0100 > #define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0200 > -- > 2.34.1 >
On 7/10/23 17:51, James Clark wrote: > Since commit bd2756811766 ("perf: Rewrite core context handling") the > relationship between perf_event_context and PMUs has changed so that > the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally > silenced no longer exists. > > Remove the capability to avoid confusion that it actually influences > any perf core behavior. This change should be a no-op. > > Signed-off-by: James Clark <james.clark@arm.com> > --- > include/linux/perf_event.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index d5628a7b5eaa..3f4d941fd6c5 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -288,7 +288,7 @@ struct perf_event_pmu_context; > #define PERF_PMU_CAP_EXTENDED_REGS 0x0008 > #define PERF_PMU_CAP_EXCLUSIVE 0x0010 > #define PERF_PMU_CAP_ITRACE 0x0020 > -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x0040 > +/* Unused 0x0040 */ Small nit, "Unused" marking might not be required here. > #define PERF_PMU_CAP_NO_EXCLUDE 0x0080 > #define PERF_PMU_CAP_AUX_OUTPUT 0x0100 > #define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0200
On 11/07/2023 13:10, Anshuman Khandual wrote: > > > On 7/10/23 17:51, James Clark wrote: >> Since commit bd2756811766 ("perf: Rewrite core context handling") the >> relationship between perf_event_context and PMUs has changed so that >> the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally >> silenced no longer exists. >> >> Remove the capability to avoid confusion that it actually influences >> any perf core behavior. This change should be a no-op. >> >> Signed-off-by: James Clark <james.clark@arm.com> >> --- >> include/linux/perf_event.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h >> index d5628a7b5eaa..3f4d941fd6c5 100644 >> --- a/include/linux/perf_event.h >> +++ b/include/linux/perf_event.h >> @@ -288,7 +288,7 @@ struct perf_event_pmu_context; >> #define PERF_PMU_CAP_EXTENDED_REGS 0x0008 >> #define PERF_PMU_CAP_EXCLUSIVE 0x0010 >> #define PERF_PMU_CAP_ITRACE 0x0020 >> -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x0040 >> +/* Unused 0x0040 */ > > Small nit, "Unused" marking might not be required here. > But then it would be very easy to miss that there is a free bit if I don't leave the comment. Is it really better without it? I could shift all the following ones down by one bit, but it would be a lot of work to make sure that nobody has hard coded some check for one of the bits instead of using the define somewhere. >> #define PERF_PMU_CAP_NO_EXCLUDE 0x0080 >> #define PERF_PMU_CAP_AUX_OUTPUT 0x0100 >> #define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0200
On 7/11/23 19:45, James Clark wrote: > > > On 11/07/2023 13:10, Anshuman Khandual wrote: >> >> >> On 7/10/23 17:51, James Clark wrote: >>> Since commit bd2756811766 ("perf: Rewrite core context handling") the >>> relationship between perf_event_context and PMUs has changed so that >>> the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally >>> silenced no longer exists. >>> >>> Remove the capability to avoid confusion that it actually influences >>> any perf core behavior. This change should be a no-op. >>> >>> Signed-off-by: James Clark <james.clark@arm.com> >>> --- >>> include/linux/perf_event.h | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h >>> index d5628a7b5eaa..3f4d941fd6c5 100644 >>> --- a/include/linux/perf_event.h >>> +++ b/include/linux/perf_event.h >>> @@ -288,7 +288,7 @@ struct perf_event_pmu_context; >>> #define PERF_PMU_CAP_EXTENDED_REGS 0x0008 >>> #define PERF_PMU_CAP_EXCLUSIVE 0x0010 >>> #define PERF_PMU_CAP_ITRACE 0x0020 >>> -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x0040 >>> +/* Unused 0x0040 */ >> >> Small nit, "Unused" marking might not be required here. >> > > But then it would be very easy to miss that there is a free bit if I > don't leave the comment. Is it really better without it? > > I could shift all the following ones down by one bit, but it would be a Sounds as a better option IMHO. > lot of work to make sure that nobody has hard coded some check for one > of the bits instead of using the define somewhere. These are not user visible ABI and hence defined in include/linux/perf_event.h to be used by drivers registering a PMU for capability enumeration. I am just wondering why they might have been hard coded any where ? > >>> #define PERF_PMU_CAP_NO_EXCLUDE 0x0080 >>> #define PERF_PMU_CAP_AUX_OUTPUT 0x0100 >>> #define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0200
On 13/07/2023 08:30, Anshuman Khandual wrote: > > > On 7/11/23 19:45, James Clark wrote: >> >> >> On 11/07/2023 13:10, Anshuman Khandual wrote: >>> >>> >>> On 7/10/23 17:51, James Clark wrote: >>>> Since commit bd2756811766 ("perf: Rewrite core context handling") the >>>> relationship between perf_event_context and PMUs has changed so that >>>> the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally >>>> silenced no longer exists. >>>> >>>> Remove the capability to avoid confusion that it actually influences >>>> any perf core behavior. This change should be a no-op. >>>> >>>> Signed-off-by: James Clark <james.clark@arm.com> >>>> --- >>>> include/linux/perf_event.h | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h >>>> index d5628a7b5eaa..3f4d941fd6c5 100644 >>>> --- a/include/linux/perf_event.h >>>> +++ b/include/linux/perf_event.h >>>> @@ -288,7 +288,7 @@ struct perf_event_pmu_context; >>>> #define PERF_PMU_CAP_EXTENDED_REGS 0x0008 >>>> #define PERF_PMU_CAP_EXCLUSIVE 0x0010 >>>> #define PERF_PMU_CAP_ITRACE 0x0020 >>>> -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x0040 >>>> +/* Unused 0x0040 */ >>> >>> Small nit, "Unused" marking might not be required here. >>> >> >> But then it would be very easy to miss that there is a free bit if I >> don't leave the comment. Is it really better without it? >> >> I could shift all the following ones down by one bit, but it would be a > > Sounds as a better option IMHO. > >> lot of work to make sure that nobody has hard coded some check for one >> of the bits instead of using the define somewhere. > > These are not user visible ABI and hence defined in include/linux/perf_event.h > to be used by drivers registering a PMU for capability enumeration. I am just > wondering why they might have been hard coded any where ? > You never know, I've seen worse! I suppose we'll find out if I change it and anything breaks. It will probably be fine though, I'll make the change on the next version. >> >>>> #define PERF_PMU_CAP_NO_EXCLUDE 0x0080 >>>> #define PERF_PMU_CAP_AUX_OUTPUT 0x0100 >>>> #define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0200
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index d5628a7b5eaa..3f4d941fd6c5 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -288,7 +288,7 @@ struct perf_event_pmu_context; #define PERF_PMU_CAP_EXTENDED_REGS 0x0008 #define PERF_PMU_CAP_EXCLUSIVE 0x0010 #define PERF_PMU_CAP_ITRACE 0x0020 -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x0040 +/* Unused 0x0040 */ #define PERF_PMU_CAP_NO_EXCLUDE 0x0080 #define PERF_PMU_CAP_AUX_OUTPUT 0x0100 #define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0200
Since commit bd2756811766 ("perf: Rewrite core context handling") the relationship between perf_event_context and PMUs has changed so that the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally silenced no longer exists. Remove the capability to avoid confusion that it actually influences any perf core behavior. This change should be a no-op. Signed-off-by: James Clark <james.clark@arm.com> --- include/linux/perf_event.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)