Messages in this thread | | | Date | Wed, 31 Aug 2022 11:40:22 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v1 5/8] perf topology: Add core_wide |
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Em Tue, Aug 30, 2022 at 09:48:43AM -0700, Ian Rogers escreveu: > It is possible to optimize metrics when all SMT threads (CPUs) on a > core are measuring events in system wide mode. For example, TMA > metrics defines CORE_CLKS for Sandybrdige as: > > if SMT is disabled: > CPU_CLK_UNHALTED.THREAD > if SMT is enabled and recording on all SMT threads: > CPU_CLK_UNHALTED.THREAD_ANY / 2 > if SMT is enabled and not recording on all SMT threads: > (CPU_CLK_UNHALTED.THREAD/2)* > (1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK ) > > That is two more events are necessary when not gathering counts on all > SMT threads. To distinguish all SMT threads on a core vs system wide > (all CPUs) call the new property core wide. Add a core wide test that > determines the property from user requested CPUs, the topology and > system wide. System wide is required as other processes running on a > SMT thread will change the counts. > > Signed-off-by: Ian Rogers <irogers@google.com> > --- > tools/perf/util/cputopo.c | 46 +++++++++++++++++++++++++++++++++++++++ > tools/perf/util/cputopo.h | 3 +++ > tools/perf/util/smt.c | 14 ++++++++++++ > tools/perf/util/smt.h | 7 ++++++ > 4 files changed, 70 insertions(+) > > diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c > index 511002e52714..1a3ff6449158 100644 > --- a/tools/perf/util/cputopo.c > +++ b/tools/perf/util/cputopo.c > @@ -172,6 +172,52 @@ bool cpu_topology__smt_on(const struct cpu_topology *topology) > return false; > } > > +bool cpu_topology__core_wide(const struct cpu_topology *topology, > + const char *user_requested_cpu_list) > +{ > + struct perf_cpu_map *user_requested_cpus; > + > + /* > + * If user_requested_cpu_list is empty then all CPUs are recorded and so > + * core_wide is true. > + */ > + if (!user_requested_cpu_list) > + return true; > + > + user_requested_cpus = perf_cpu_map__new(user_requested_cpu_list);
Don't we need a NULL test here?
> + /* Check that every user requested CPU is the complete set of SMT threads on a core. */ > + for (u32 i = 0; i < topology->core_cpus_lists; i++) { > + const char *core_cpu_list = topology->core_cpus_list[i]; > + struct perf_cpu_map *core_cpus = perf_cpu_map__new(core_cpu_list);
Here too, no?
> + struct perf_cpu cpu; > + int idx; > + bool has_first, first = true; > + > + perf_cpu_map__for_each_cpu(cpu, idx, core_cpus) { > + if (first) { > + has_first = perf_cpu_map__has(user_requested_cpus, cpu); > + first = false; > + } else { > + /* > + * If the first core CPU is user requested then > + * all subsequent CPUs in the core must be user > + * requested too. If the first CPU isn't user > + * requested then none of the others must be > + * too. > + */ > + if (perf_cpu_map__has(user_requested_cpus, cpu) != has_first) { > + perf_cpu_map__put(core_cpus); > + perf_cpu_map__put(user_requested_cpus); > + return false; > + } > + } > + } > + perf_cpu_map__put(core_cpus); > + } > + perf_cpu_map__put(user_requested_cpus); > + return true; > +} > + > static bool has_die_topology(void) > { > char filename[MAXPATHLEN]; > diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h > index 469db775a13c..969e5920a00e 100644 > --- a/tools/perf/util/cputopo.h > +++ b/tools/perf/util/cputopo.h > @@ -60,6 +60,9 @@ struct cpu_topology *cpu_topology__new(void); > void cpu_topology__delete(struct cpu_topology *tp); > /* Determine from the core list whether SMT was enabled. */ > bool cpu_topology__smt_on(const struct cpu_topology *topology); > +/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */ > +bool cpu_topology__core_wide(const struct cpu_topology *topology, > + const char *user_requested_cpu_list); > > struct numa_topology *numa_topology__new(void); > void numa_topology__delete(struct numa_topology *tp); > diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c > index ce90c4ee4138..994e9e418227 100644 > --- a/tools/perf/util/smt.c > +++ b/tools/perf/util/smt.c > @@ -21,3 +21,17 @@ bool smt_on(const struct cpu_topology *topology) > cached = true; > return cached_result; > } > + > +bool core_wide(bool system_wide, const char *user_requested_cpu_list, > + const struct cpu_topology *topology) > +{ > + /* If not everything running on a core is being recorded then we can't use core_wide. */ > + if (!system_wide) > + return false; > + > + /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */ > + if (!smt_on(topology)) > + return true; > + > + return cpu_topology__core_wide(topology, user_requested_cpu_list); > +} > diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h > index e26999c6b8d4..ae9095f2c38c 100644 > --- a/tools/perf/util/smt.h > +++ b/tools/perf/util/smt.h > @@ -7,4 +7,11 @@ struct cpu_topology; > /* Returns true if SMT (aka hyperthreading) is enabled. */ > bool smt_on(const struct cpu_topology *topology); > > +/* > + * Returns true when system wide and all SMT threads for a core are in the > + * user_requested_cpus map. > + */ > +bool core_wide(bool system_wide, const char *user_requested_cpu_list, > + const struct cpu_topology *topology); > + > #endif /* __SMT_H */ > -- > 2.37.2.672.g94769d06f0-goog
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- Arnaldo
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