| Message ID | 1652705738-1628-1-git-send-email-quic_c_spathi@quicinc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [V4] arm64: perf: Set PMCR.X of PMCR_EL0 during pmu reset | expand |
On Mon, May 16, 2022 at 06:25:38PM +0530, Srinivasarao Pathipati wrote: > Enable exporting of events over PMU event export bus by setting > PMCR.X of PMCR_EL0 during pmu reset. > > As it impacts power consumption make it configurable at bootup > with kernel arguments and at runtime with sysctl. > > Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com> > --- > Changes since V3: > - export bit is now configurable with sysctl > - enabling export bit on reset instead of retaining > > Changes since V2: > Done below changes as per Will's comments > - enabling pmcr_x now configurable with kernel parameters and > by default it is disabled. > > Changes since V1: > - Preserving only PMCR_X bit as per Robin Murphy's comment. > --- > Documentation/admin-guide/kernel-parameters.txt | 4 ++++ > Documentation/admin-guide/sysctl/kernel.rst | 8 ++++++++ > arch/arm64/kernel/perf_event.c | 15 +++++++++++++++ > include/linux/perf_event.h | 1 + > kernel/sysctl.c | 12 ++++++++++++ > 5 files changed, 40 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index de3da15..2139b81 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -5150,6 +5150,10 @@ > Useful for devices that are detected asynchronously > (e.g. USB and MMC devices). > > + export_pmu_events > + [KNL] Sets export bit of PMCR_EL0 to enable the exporting of > + events over PMU event export bus. Sorry, I should've been clearer ahbout this before: if you add a sysctl, then you get the kernel cmdline option for free via something like "sysctl.kernel.export_pmu_events=foo", so I think you can drop this and the early_param(). > + > retain_initrd [RAM] Keep initrd memory after extraction > > rfkill.default_state= > diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst > index ddccd10..8fbc3a0 100644 > --- a/Documentation/admin-guide/sysctl/kernel.rst > +++ b/Documentation/admin-guide/sysctl/kernel.rst > @@ -892,6 +892,14 @@ The default value is 0 (access disabled). > > See Documentation/arm64/perf.rst for more information. > > +export_pmu_events > +================= You should add something like "(arm64 only)" to the title. > +Controls the export bit(4th bit) of PMCR_EL0 which enables the exporting of Just say "Controls the PMU export bit (PMCR_EL0.X), which enables ...". > +events over an IMPLEMENTATION DEFINED PMU event export bus to another device. > + > +0: disables exporting of events > + > +1: enables exporting of events Please state that the default value is 0. > pid_max > ======= > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index cb69ff1..271a8c6 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -34,6 +34,7 @@ > #define ARMV8_THUNDER_PERFCTR_L1I_CACHE_PREF_ACCESS 0xEC > #define ARMV8_THUNDER_PERFCTR_L1I_CACHE_PREF_MISS 0xED > > +int sysctl_export_pmu_events __read_mostly; > /* > * ARMv8 Architectural defined events, not all of these may > * be supported on any given implementation. Unsupported events will > @@ -1025,6 +1026,17 @@ static int armv8pmu_filter_match(struct perf_event *event) > return evtype != ARMV8_PMUV3_PERFCTR_CHAIN; > } > > +static int __init export_pmu_events(char *str) > +{ > + /* Exporting of events can be enabled at runtime with sysctl or > + * statically at bootup with kernel parameters. > + */ > + sysctl_export_pmu_events = 1; > + return 0; > +} > + > +early_param("export_pmu_events", export_pmu_events); > + > static void armv8pmu_reset(void *info) > { > struct arm_pmu *cpu_pmu = (struct arm_pmu *)info; > @@ -1047,6 +1059,9 @@ static void armv8pmu_reset(void *info) > if (armv8pmu_has_long_event(cpu_pmu)) > pmcr |= ARMV8_PMU_PMCR_LP; > > + if (sysctl_export_pmu_events) > + pmcr |= ARMV8_PMU_PMCR_X; > + > armv8pmu_pmcr_write(pmcr); Hmm, I think this reset path only runs when initialising/onlining a CPU, so it's not a great user interface where the sysctl is concerned. It's probably better to hook armv8pmu_start() for this. > } > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index da75956..7790328 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -1311,6 +1311,7 @@ extern void put_callchain_entry(int rctx); > > extern int sysctl_perf_event_max_stack; > extern int sysctl_perf_event_max_contexts_per_stack; > +extern int sysctl_export_pmu_events; > > static inline int perf_callchain_store_context(struct perf_callchain_entry_ctx *ctx, u64 ip) > { > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index e52b6e3..3b751a2e 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -2008,6 +2008,18 @@ static struct ctl_table kern_table[] = { > .extra2 = SYSCTL_ONE_THOUSAND, > }, > #endif > +#ifdef CONFIG_HW_PERF_EVENTS > + { > + .procname = "export_pmu_events", > + .data = &sysctl_export_pmu_events, > + .maxlen = sizeof(int), > + .mode = 0644, > + .proc_handler = proc_dointvec_minmax, > + .extra1 = SYSCTL_ZERO, > + .extra2 = SYSCTL_ONE, > + > + }, > +#endif Since this is arm64-specific, it should live in the arm64 code and not here. See how we already register 'armv8_pmu_sysctl_table' for the ARMv8 PMU. Will
On 5/17/2022 6:38 PM, Will Deacon wrote: > On Mon, May 16, 2022 at 06:25:38PM +0530, Srinivasarao Pathipati wrote: >> Enable exporting of events over PMU event export bus by setting >> PMCR.X of PMCR_EL0 during pmu reset. >> >> As it impacts power consumption make it configurable at bootup >> with kernel arguments and at runtime with sysctl. >> >> Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com> >> --- >> Changes since V3: >> - export bit is now configurable with sysctl >> - enabling export bit on reset instead of retaining >> >> Changes since V2: >> Done below changes as per Will's comments >> - enabling pmcr_x now configurable with kernel parameters and >> by default it is disabled. >> >> Changes since V1: >> - Preserving only PMCR_X bit as per Robin Murphy's comment. >> --- >> Documentation/admin-guide/kernel-parameters.txt | 4 ++++ >> Documentation/admin-guide/sysctl/kernel.rst | 8 ++++++++ >> arch/arm64/kernel/perf_event.c | 15 +++++++++++++++ >> include/linux/perf_event.h | 1 + >> kernel/sysctl.c | 12 ++++++++++++ >> 5 files changed, 40 insertions(+) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index de3da15..2139b81 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -5150,6 +5150,10 @@ >> Useful for devices that are detected asynchronously >> (e.g. USB and MMC devices). >> >> + export_pmu_events >> + [KNL] Sets export bit of PMCR_EL0 to enable the exporting of >> + events over PMU event export bus. > Sorry, I should've been clearer ahbout this before: if you add a sysctl, > then you get the kernel cmdline option for free via something like > "sysctl.kernel.export_pmu_events=foo", so I think you can drop this and > the early_param(). Thanks for your suggestion , I tried this method and observed that pmu_reset is getting called even before kernel argument updated the sysctl variable. So exporting is not happening at early boot. >> + >> retain_initrd [RAM] Keep initrd memory after extraction >> >> rfkill.default_state= >> diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst >> index ddccd10..8fbc3a0 100644 >> --- a/Documentation/admin-guide/sysctl/kernel.rst >> +++ b/Documentation/admin-guide/sysctl/kernel.rst >> @@ -892,6 +892,14 @@ The default value is 0 (access disabled). >> >> See Documentation/arm64/perf.rst for more information. >> >> +export_pmu_events >> +================= > You should add something like "(arm64 only)" to the title. > >> +Controls the export bit(4th bit) of PMCR_EL0 which enables the exporting of > Just say "Controls the PMU export bit (PMCR_EL0.X), which enables ...". > >> +events over an IMPLEMENTATION DEFINED PMU event export bus to another device. >> + >> +0: disables exporting of events >> + >> +1: enables exporting of events > Please state that the default value is 0. > >> pid_max >> ======= >> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c >> index cb69ff1..271a8c6 100644 >> --- a/arch/arm64/kernel/perf_event.c >> +++ b/arch/arm64/kernel/perf_event.c >> @@ -34,6 +34,7 @@ >> #define ARMV8_THUNDER_PERFCTR_L1I_CACHE_PREF_ACCESS 0xEC >> #define ARMV8_THUNDER_PERFCTR_L1I_CACHE_PREF_MISS 0xED >> >> +int sysctl_export_pmu_events __read_mostly; >> /* >> * ARMv8 Architectural defined events, not all of these may >> * be supported on any given implementation. Unsupported events will >> @@ -1025,6 +1026,17 @@ static int armv8pmu_filter_match(struct perf_event *event) >> return evtype != ARMV8_PMUV3_PERFCTR_CHAIN; >> } >> >> +static int __init export_pmu_events(char *str) >> +{ >> + /* Exporting of events can be enabled at runtime with sysctl or >> + * statically at bootup with kernel parameters. >> + */ >> + sysctl_export_pmu_events = 1; >> + return 0; >> +} >> + >> +early_param("export_pmu_events", export_pmu_events); >> + >> static void armv8pmu_reset(void *info) >> { >> struct arm_pmu *cpu_pmu = (struct arm_pmu *)info; >> @@ -1047,6 +1059,9 @@ static void armv8pmu_reset(void *info) >> if (armv8pmu_has_long_event(cpu_pmu)) >> pmcr |= ARMV8_PMU_PMCR_LP; >> >> + if (sysctl_export_pmu_events) >> + pmcr |= ARMV8_PMU_PMCR_X; >> + >> armv8pmu_pmcr_write(pmcr); > > Hmm, I think this reset path only runs when initialising/onlining a CPU, > so it's not a great user interface where the sysctl is concerned. It's > probably better to hook armv8pmu_start() for this. > >> } >> >> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h >> index da75956..7790328 100644 >> --- a/include/linux/perf_event.h >> +++ b/include/linux/perf_event.h >> @@ -1311,6 +1311,7 @@ extern void put_callchain_entry(int rctx); >> >> extern int sysctl_perf_event_max_stack; >> extern int sysctl_perf_event_max_contexts_per_stack; >> +extern int sysctl_export_pmu_events; >> >> static inline int perf_callchain_store_context(struct perf_callchain_entry_ctx *ctx, u64 ip) >> { >> diff --git a/kernel/sysctl.c b/kernel/sysctl.c >> index e52b6e3..3b751a2e 100644 >> --- a/kernel/sysctl.c >> +++ b/kernel/sysctl.c >> @@ -2008,6 +2008,18 @@ static struct ctl_table kern_table[] = { >> .extra2 = SYSCTL_ONE_THOUSAND, >> }, >> #endif >> +#ifdef CONFIG_HW_PERF_EVENTS >> + { >> + .procname = "export_pmu_events", >> + .data = &sysctl_export_pmu_events, >> + .maxlen = sizeof(int), >> + .mode = 0644, >> + .proc_handler = proc_dointvec_minmax, >> + .extra1 = SYSCTL_ZERO, >> + .extra2 = SYSCTL_ONE, >> + >> + }, >> +#endif > Since this is arm64-specific, it should live in the arm64 code and not > here. See how we already register 'armv8_pmu_sysctl_table' for the ARMv8 > PMU. > > Will
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index de3da15..2139b81 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5150,6 +5150,10 @@ Useful for devices that are detected asynchronously (e.g. USB and MMC devices). + export_pmu_events + [KNL] Sets export bit of PMCR_EL0 to enable the exporting of + events over PMU event export bus. + retain_initrd [RAM] Keep initrd memory after extraction rfkill.default_state= diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index ddccd10..8fbc3a0 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -892,6 +892,14 @@ The default value is 0 (access disabled). See Documentation/arm64/perf.rst for more information. +export_pmu_events +================= +Controls the export bit(4th bit) of PMCR_EL0 which enables the exporting of +events over an IMPLEMENTATION DEFINED PMU event export bus to another device. + +0: disables exporting of events + +1: enables exporting of events pid_max ======= diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index cb69ff1..271a8c6 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -34,6 +34,7 @@ #define ARMV8_THUNDER_PERFCTR_L1I_CACHE_PREF_ACCESS 0xEC #define ARMV8_THUNDER_PERFCTR_L1I_CACHE_PREF_MISS 0xED +int sysctl_export_pmu_events __read_mostly; /* * ARMv8 Architectural defined events, not all of these may * be supported on any given implementation. Unsupported events will @@ -1025,6 +1026,17 @@ static int armv8pmu_filter_match(struct perf_event *event) return evtype != ARMV8_PMUV3_PERFCTR_CHAIN; } +static int __init export_pmu_events(char *str) +{ + /* Exporting of events can be enabled at runtime with sysctl or + * statically at bootup with kernel parameters. + */ + sysctl_export_pmu_events = 1; + return 0; +} + +early_param("export_pmu_events", export_pmu_events); + static void armv8pmu_reset(void *info) { struct arm_pmu *cpu_pmu = (struct arm_pmu *)info; @@ -1047,6 +1059,9 @@ static void armv8pmu_reset(void *info) if (armv8pmu_has_long_event(cpu_pmu)) pmcr |= ARMV8_PMU_PMCR_LP; + if (sysctl_export_pmu_events) + pmcr |= ARMV8_PMU_PMCR_X; + armv8pmu_pmcr_write(pmcr); } diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index da75956..7790328 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1311,6 +1311,7 @@ extern void put_callchain_entry(int rctx); extern int sysctl_perf_event_max_stack; extern int sysctl_perf_event_max_contexts_per_stack; +extern int sysctl_export_pmu_events; static inline int perf_callchain_store_context(struct perf_callchain_entry_ctx *ctx, u64 ip) { diff --git a/kernel/sysctl.c b/kernel/sysctl.c index e52b6e3..3b751a2e 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2008,6 +2008,18 @@ static struct ctl_table kern_table[] = { .extra2 = SYSCTL_ONE_THOUSAND, }, #endif +#ifdef CONFIG_HW_PERF_EVENTS + { + .procname = "export_pmu_events", + .data = &sysctl_export_pmu_events, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + + }, +#endif { .procname = "panic_on_warn", .data = &panic_on_warn,
Enable exporting of events over PMU event export bus by setting PMCR.X of PMCR_EL0 during pmu reset. As it impacts power consumption make it configurable at bootup with kernel arguments and at runtime with sysctl. Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com> --- Changes since V3: - export bit is now configurable with sysctl - enabling export bit on reset instead of retaining Changes since V2: Done below changes as per Will's comments - enabling pmcr_x now configurable with kernel parameters and by default it is disabled. Changes since V1: - Preserving only PMCR_X bit as per Robin Murphy's comment. --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ Documentation/admin-guide/sysctl/kernel.rst | 8 ++++++++ arch/arm64/kernel/perf_event.c | 15 +++++++++++++++ include/linux/perf_event.h | 1 + kernel/sysctl.c | 12 ++++++++++++ 5 files changed, 40 insertions(+)