Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Mon, 16 Jan 2023 19:27:28 +0800 | Subject | Re: [PATCH v7 1/9] perf pmu: Add #slots literal support for arm64 | From | Jing Zhang <> |
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在 2023/1/16 下午1:59, Ian Rogers 写道: > On Sun, Jan 15, 2023 at 6:58 PM Jing Zhang <renyu.zj@linux.alibaba.com> wrote: >> >> 在 2023/1/15 上午6:15, Ian Rogers 写道: >>> On Fri, Jan 13, 2023 at 1:22 AM Jing Zhang <renyu.zj@linux.alibaba.com> wrote: >>>> >>>> The slots in each architecture may be different, so add #slots literal >>>> to obtain the slots of different architectures, and the #slots can be >>>> applied in the metric. Currently, The #slots just support for arm64, >>>> and other architectures will return NAN. >>>> >>>> On arm64, the value of slots is from the register PMMIR_EL1.SLOT, which >>>> I can read in /sys/bus/event_source/device/armv8_pmuv3_*/caps/slots. >>>> PMMIR_EL1.SLOT might read as zero if the PMU version is lower than >>>> ID_AA64DFR0_EL1_PMUVer_V3P4 or the STALL_SLOT event is not implemented. >>>> >>>> Signed-off-by: Jing Zhang <renyu.zj@linux.alibaba.com> >>>> --- >>>> tools/perf/arch/arm64/util/pmu.c | 34 ++++++++++++++++++++++++++++++++-- >>>> tools/perf/util/expr.c | 5 +++++ >>>> tools/perf/util/pmu.c | 6 ++++++ >>>> tools/perf/util/pmu.h | 1 + >>>> 4 files changed, 44 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/tools/perf/arch/arm64/util/pmu.c b/tools/perf/arch/arm64/util/pmu.c >>>> index 477e513..5f8667b 100644 >>>> --- a/tools/perf/arch/arm64/util/pmu.c >>>> +++ b/tools/perf/arch/arm64/util/pmu.c >>>> @@ -3,8 +3,9 @@ >>>> #include <internal/cpumap.h> >>>> #include "../../../util/cpumap.h" >>>> #include "../../../util/pmu.h" >>>> +#include <api/fs/fs.h> >>>> >>>> -const struct pmu_events_table *pmu_events_table__find(void) >>>> +static struct perf_pmu *pmu_core__find_same(void) >>> >>> I'm not sure "find_same" is the best name here. I suspect it should be >>> "find_core_pmu" which would agree with is_arm_pmu_core. Unfortunately >>> "core" has become an overloaded term sometimes used interchangeably >>> with CPU, hyperthread or SMT thread, it was a model name for Intel and >>> it is used to distinguish a set of SMT threads running together from a >>> single one. Anyway, for consistency I think perf_pmu__find_core_pmu is >>> the most appropriate name (or pmu__find_core_pmu, I'm not sure why we >>> get the extra perf_ prefix sometimes, in general that indicates the >>> functionality is in libperf). >>> >> >> The reason for using "pmu_core__find_same" before is to indicate that we're >> only dealing with homogeneous cores. And in the tools/perf/util/pmu.c file, >> most of the static functions have "pmu_" prefix, maybe we can use >> "pmu_find_same_core_pmu"? Ian, John, what do you think? > > I wouldn't necessarily worry about hybrid given #slots is currently > ARM specific. For hybrid we'd need to know the CPU for the metric. We > do have the list of CPUs (really hyper/SMT threads) that were > requested for the metric: > https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/util/expr.h?h=perf/core#n9 > We use it to compute the #core_wide literal. We need the value early > before events are created, hence the string format. You could search > pmus looking for a PMU that isn't uncore and has matching CPUs, but > AMD has multiple core/hardware PMUs (hence Ravi's most recent work) > and so I suspect we'd need to extend PMU to make this work. We've > solved a similar problem to this with the source_count metric > function, that returns a number of aliased events. We could do > something like: > slots(INST_RETIRED.MACRO_FUSED) > and then from the event get the PMU, from the PMU get the CPUs, from a > CPU get the slots. In that case it may just be cleaner to pass the PMU > name to the slots function, so: > slots(cpu_core) or slots(cpu_atom) > But the parser wouldn't understand that cpu_core or cpu_atom were PMU > names and would try to handle them as events or metric references. > > Again, I think ignoring the hybrid case is fine in this case. Using > "same" in the function name to imply "not hybrid" I don't think works, > so I think something like pmu__find_core_pmu is best. You could have a > comment and also a: > assert(!perf_pmu__is_hybrid(pmu->name)); > Ultimately I'd like to get rid of all notions of hybrid and just pair > events with a PMU. I recently cleaned this up in builtin-list.c. >
Ok, you are right, I follow your suggestion and use pmu__find_core_pmu.
I think “if (pmu->cpus->nr != cpu__max_cpu().cpu)” in the original code and “assert(!perf_pmu__is_hybrid(pmu->name))” have the same effect, so I will not change it.
> Thanks, > Ian > >> Thanks, >> Jing >> >>> Aside from that, lgtm. Thanks, >>> Ian >>> >>>> { >>>> struct perf_pmu *pmu = NULL; >>>> >>>> @@ -19,8 +20,37 @@ const struct pmu_events_table *pmu_events_table__find(void) >>>> if (pmu->cpus->nr != cpu__max_cpu().cpu) >>>> return NULL; >>>> >>>> - return perf_pmu__find_table(pmu); >>>> + return pmu; >>>> } >>>> >>>> return NULL; >>>> } >>>> + >>>> +const struct pmu_events_table *pmu_events_table__find(void) >>>> +{ >>>> + struct perf_pmu *pmu = pmu_core__find_same(); >>>> + >>>> + if (pmu) >>>> + return perf_pmu__find_table(pmu); >>>> + >>>> + return NULL; >>>> +} >>>> + >>>> +double perf_pmu__cpu_slots_per_cycle(void) >>>> +{ >>>> + char path[PATH_MAX]; >>>> + unsigned long long slots = 0; >>>> + struct perf_pmu *pmu = pmu_core__find_same(); >>>> + >>>> + if (pmu) { >>>> + scnprintf(path, PATH_MAX, >>>> + EVENT_SOURCE_DEVICE_PATH "%s/caps/slots", pmu->name); >>>> + /* >>>> + * The value of slots is not greater than 32 bits, but sysfs__read_int >>>> + * can't read value with 0x prefix, so use sysfs__read_ull instead. >>>> + */ >>>> + sysfs__read_ull(path, &slots); >>>> + } >>>> + >>>> + return (double)slots; >>>> +} >>>> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c >>>> index 00dcde3..9d3076a 100644 >>>> --- a/tools/perf/util/expr.c >>>> +++ b/tools/perf/util/expr.c >>>> @@ -19,6 +19,7 @@ >>>> #include <linux/zalloc.h> >>>> #include <ctype.h> >>>> #include <math.h> >>>> +#include "pmu.h" >>>> >>>> #ifdef PARSER_DEBUG >>>> extern int expr_debug; >>>> @@ -448,6 +449,10 @@ double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx >>>> result = topology->core_cpus_lists; >>>> goto out; >>>> } >>>> + if (!strcmp("#slots", literal)) { >>>> + result = perf_pmu__cpu_slots_per_cycle() ?: NAN; >>>> + goto out; >>>> + } >>>> >>>> pr_err("Unrecognized literal '%s'", literal); >>>> out: >>>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c >>>> index 2bdeb89..cbb4fbf 100644 >>>> --- a/tools/perf/util/pmu.c >>>> +++ b/tools/perf/util/pmu.c >>>> @@ -19,6 +19,7 @@ >>>> #include <regex.h> >>>> #include <perf/cpumap.h> >>>> #include <fnmatch.h> >>>> +#include <math.h> >>>> #include "debug.h" >>>> #include "evsel.h" >>>> #include "pmu.h" >>>> @@ -1993,3 +1994,8 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus, >>>> *ucpus_ptr = unmatched_cpus; >>>> return 0; >>>> } >>>> + >>>> +double __weak perf_pmu__cpu_slots_per_cycle(void) >>>> +{ >>>> + return NAN; >>>> +} >>>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h >>>> index 69ca000..fd414ba 100644 >>>> --- a/tools/perf/util/pmu.h >>>> +++ b/tools/perf/util/pmu.h >>>> @@ -259,4 +259,5 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus, >>>> >>>> char *pmu_find_real_name(const char *name); >>>> char *pmu_find_alias_name(const char *name); >>>> +double perf_pmu__cpu_slots_per_cycle(void); >>>> #endif /* __PMU_H */ >>>> -- >>>> 1.8.3.1 >>>>
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