From cc2c4e26ece19b4118f059f3a526c048793e58af Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Wed, 31 Aug 2022 10:49:23 -0700 Subject: perf topology: Add core_wide 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 Cc: Ahmad Yasin Cc: Alexander Shishkin Cc: Andi Kleen Cc: Caleb Biggers Cc: Florian Fischer Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Kan Liang Cc: Kshipra Bopardikar Cc: Mark Rutland Cc: Miaoqian Lin Cc: Namhyung Kim Cc: Perry Taylor Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Richter Cc: Xing Zhengjun Link: https://lore.kernel.org/r/20220831174926.579643-5-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- 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); + /* 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); + 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 */ -- cgit v1.2.3