Messages in this thread | | | Subject | Re: [PATCH V2 1/2] powerpc/perf: Add support for caps under sysfs in powerpc | From | Athira Rajeev <> | Date | Fri, 20 May 2022 11:44:52 +0530 |
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> On 20-May-2022, at 3:06 AM, Ian Rogers <irogers@google.com> wrote: > > On Thu, May 19, 2022 at 4:29 AM Athira Rajeev > <atrajeev@linux.vnet.ibm.com> wrote: >> >>> On 19-May-2022, at 10:12 AM, Ian Rogers <irogers@google.com> wrote: >>> >>> On Wed, May 18, 2022 at 1:55 AM Athira Rajeev >>> <atrajeev@linux.vnet.ibm.com> wrote: >>>> >>>> Add caps support under "/sys/bus/event_source/devices/<pmu>/" >>>> for powerpc. This directory can be used to expose some of the >>>> specific features that powerpc PMU supports to the user. >>>> Example: pmu_name. The name of PMU registered will depend on >>>> platform, say power9 or power10 or it could be Generic Compat >>>> PMU. >>>> >>>> Currently the only way to know which is the registered >>>> PMU is from the dmesg logs. But clearing the dmesg will make it >>>> difficult to know exact PMU backend used. And even extracting >>>> from dmesg will be complicated, as we need to parse the dmesg >>>> logs and add filters for pmu name. Whereas by exposing it via >>>> caps will make it easy as we just need to directly read it from >>>> the sysfs. >>> >>> For ARM and x86 in the perf tool this is normally done through a cpuid >>> like function, is there a reason to differ on Power? >>> >>> Thanks, >>> Ian >> >> Hi Ian, >> >> Thanks for review. The information from cpuid or cpuinfo will provide >> us the information of the platform/model/machine etc. In case of powerpc, >> we have one case where, though platform points to specific generation of the >> processor, say power9 or power10, the registered PMU could point to >> different one. To be specific, this is named as Generic Compat PMU which >> is a fallback PMU. This gets registered when the distro doesn't have support >> for platform specific PMU. In that case distro will have a Generic >> Compat PMU registered which supports basic features for performance monitoring. >> This information can't be fetched from the cpuid data since that will point >> to current platform. >> >> So the pmu_name exposed via "caps" will be useful to detect the PMU >> registered and also we target to use this information in some of our >> selftests. > > Thanks, I've no problem with the change. Do we need to do a similar > discovery in the perf tool on old kernels? Perhaps then this > information could be exposed in the perf list command for self tests.
Hi Ian,
Thanks for review. Thats good one to have. I see in perf tools, we are parsing caps data : "env->cpu_pmu_caps" already. I will check on how this is used and option of having in perf list. After checking, I will send a follow up patch for the same.
Thanks Athira > > Thanks, > Ian > >> Thanks >> Athira >>> >>>> Add a caps directory to /sys/bus/event_source/devices/cpu/ >>>> for power8, power9, power10 and generic compat PMU in respective >>>> PMU driver code. Update the pmu_name file under caps folder >>>> in core-book3s using "attr_update". >>>> >>>> The information exposed currently: >>>> - pmu_name : Underlying PMU name from the driver >>>> >>>> Example result with power9 pmu: >>>> >>>> # ls /sys/bus/event_source/devices/cpu/caps >>>> pmu_name >>>> >>>> # cat /sys/bus/event_source/devices/cpu/caps/pmu_name >>>> POWER9 >>>> >>>> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com> >>>> --- >>>> Changelog: >>>> v1 -> v2: >>>> Move the show function as generic in core-book3s >>>> and update show function using sysfs_emit and ppmu->name >>>> Added Documention for this ABI in patch 2. >>>> Notes: The caps directory is implemented in PMU for other >>>> architectures already. Reference commit for x86: >>>> commit b00233b53065 ("perf/x86: Export some PMU attributes in caps/ directory") >>>> >>>> arch/powerpc/perf/core-book3s.c | 31 ++++++++++++++++++++++++++ >>>> arch/powerpc/perf/generic-compat-pmu.c | 10 +++++++++ >>>> arch/powerpc/perf/power10-pmu.c | 10 +++++++++ >>>> arch/powerpc/perf/power8-pmu.c | 10 +++++++++ >>>> arch/powerpc/perf/power9-pmu.c | 10 +++++++++ >>>> 5 files changed, 71 insertions(+) >>>> >>>> diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c >>>> index b5b42cf0a703..a208f502a80b 100644 >>>> --- a/arch/powerpc/perf/core-book3s.c >>>> +++ b/arch/powerpc/perf/core-book3s.c >>>> @@ -2488,6 +2488,33 @@ static int power_pmu_prepare_cpu(unsigned int cpu) >>>> return 0; >>>> } >>>> >>>> +static ssize_t pmu_name_show(struct device *cdev, >>>> + struct device_attribute *attr, >>>> + char *buf) >>>> +{ >>>> + if (ppmu) >>>> + return sysfs_emit(buf, "%s\n", ppmu->name); >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static DEVICE_ATTR_RO(pmu_name); >>>> + >>>> +static struct attribute *pmu_caps_attrs[] = { >>>> + &dev_attr_pmu_name.attr, >>>> + NULL >>>> +}; >>>> + >>>> +static const struct attribute_group pmu_caps_group = { >>>> + .name = "caps", >>>> + .attrs = pmu_caps_attrs, >>>> +}; >>>> + >>>> +static const struct attribute_group *pmu_caps_groups[] = { >>>> + &pmu_caps_group, >>>> + NULL, >>>> +}; >>>> + >>>> int __init register_power_pmu(struct power_pmu *pmu) >>>> { >>>> if (ppmu) >>>> @@ -2498,6 +2525,10 @@ int __init register_power_pmu(struct power_pmu *pmu) >>>> pmu->name); >>>> >>>> power_pmu.attr_groups = ppmu->attr_groups; >>>> + >>>> + if (ppmu->flags & PPMU_ARCH_207S) >>>> + power_pmu.attr_update = pmu_caps_groups; >>>> + >>>> power_pmu.capabilities |= (ppmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS); >>>> >>>> #ifdef MSR_HV >>>> diff --git a/arch/powerpc/perf/generic-compat-pmu.c b/arch/powerpc/perf/generic-compat-pmu.c >>>> index f3db88aee4dd..817c69863038 100644 >>>> --- a/arch/powerpc/perf/generic-compat-pmu.c >>>> +++ b/arch/powerpc/perf/generic-compat-pmu.c >>>> @@ -151,9 +151,19 @@ static const struct attribute_group generic_compat_pmu_format_group = { >>>> .attrs = generic_compat_pmu_format_attr, >>>> }; >>>> >>>> +static struct attribute *generic_compat_pmu_caps_attrs[] = { >>>> + NULL >>>> +}; >>>> + >>>> +static struct attribute_group generic_compat_pmu_caps_group = { >>>> + .name = "caps", >>>> + .attrs = generic_compat_pmu_caps_attrs, >>>> +}; >>>> + >>>> static const struct attribute_group *generic_compat_pmu_attr_groups[] = { >>>> &generic_compat_pmu_format_group, >>>> &generic_compat_pmu_events_group, >>>> + &generic_compat_pmu_caps_group, >>>> NULL, >>>> }; >>>> >>>> diff --git a/arch/powerpc/perf/power10-pmu.c b/arch/powerpc/perf/power10-pmu.c >>>> index c6d51e7093cf..d1adcd9f52e2 100644 >>>> --- a/arch/powerpc/perf/power10-pmu.c >>>> +++ b/arch/powerpc/perf/power10-pmu.c >>>> @@ -258,6 +258,15 @@ static const struct attribute_group power10_pmu_format_group = { >>>> .attrs = power10_pmu_format_attr, >>>> }; >>>> >>>> +static struct attribute *power10_pmu_caps_attrs[] = { >>>> + NULL >>>> +}; >>>> + >>>> +static struct attribute_group power10_pmu_caps_group = { >>>> + .name = "caps", >>>> + .attrs = power10_pmu_caps_attrs, >>>> +}; >>>> + >>>> static const struct attribute_group *power10_pmu_attr_groups_dd1[] = { >>>> &power10_pmu_format_group, >>>> &power10_pmu_events_group_dd1, >>>> @@ -267,6 +276,7 @@ static const struct attribute_group *power10_pmu_attr_groups_dd1[] = { >>>> static const struct attribute_group *power10_pmu_attr_groups[] = { >>>> &power10_pmu_format_group, >>>> &power10_pmu_events_group, >>>> + &power10_pmu_caps_group, >>>> NULL, >>>> }; >>>> >>>> diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c >>>> index e37b1e714d2b..2518f5375d4a 100644 >>>> --- a/arch/powerpc/perf/power8-pmu.c >>>> +++ b/arch/powerpc/perf/power8-pmu.c >>>> @@ -187,9 +187,19 @@ static const struct attribute_group power8_pmu_events_group = { >>>> .attrs = power8_events_attr, >>>> }; >>>> >>>> +static struct attribute *power8_pmu_caps_attrs[] = { >>>> + NULL >>>> +}; >>>> + >>>> +static struct attribute_group power8_pmu_caps_group = { >>>> + .name = "caps", >>>> + .attrs = power8_pmu_caps_attrs, >>>> +}; >>>> + >>>> static const struct attribute_group *power8_pmu_attr_groups[] = { >>>> &isa207_pmu_format_group, >>>> &power8_pmu_events_group, >>>> + &power8_pmu_caps_group, >>>> NULL, >>>> }; >>>> >>>> diff --git a/arch/powerpc/perf/power9-pmu.c b/arch/powerpc/perf/power9-pmu.c >>>> index c393e837648e..5c654ce1a417 100644 >>>> --- a/arch/powerpc/perf/power9-pmu.c >>>> +++ b/arch/powerpc/perf/power9-pmu.c >>>> @@ -258,9 +258,19 @@ static const struct attribute_group power9_pmu_format_group = { >>>> .attrs = power9_pmu_format_attr, >>>> }; >>>> >>>> +static struct attribute *power9_pmu_caps_attrs[] = { >>>> + NULL >>>> +}; >>>> + >>>> +static struct attribute_group power9_pmu_caps_group = { >>>> + .name = "caps", >>>> + .attrs = power9_pmu_caps_attrs, >>>> +}; >>>> + >>>> static const struct attribute_group *power9_pmu_attr_groups[] = { >>>> &power9_pmu_format_group, >>>> &power9_pmu_events_group, >>>> + &power9_pmu_caps_group, >>>> NULL, >>>> }; >>>> >>>> -- >>>> 2.31.1
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