From c760174401f605cf63314d3817069a40945f0e0b Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Mon, 10 Feb 2025 11:12:31 -0800 Subject: [PATCH] perf cpumap: Reduce cpu size from int to int16_t Fewer than 32k logical CPUs are currently supported by perf. A cpumap is indexed by an integer (see perf_cpu_map__cpu) yielding a perf_cpu that wraps a 4-byte int for the logical CPU - the wrapping is done deliberately to avoid confusing a logical CPU with an index into a cpumap. Using a 4-byte int within the perf_cpu is larger than required so this patch reduces it to the 2-byte int16_t. For a cpumap containing 16 entries this will reduce the array size from 64 to 32 bytes. For very large servers with lots of logical CPUs the size savings will be greater. Signed-off-by: Ian Rogers Reviewed-by: James Clark Link: https://lore.kernel.org/r/20250210191231.156294-1-irogers@google.com Signed-off-by: Namhyung Kim --- tools/lib/perf/cpumap.c | 8 ++-- tools/lib/perf/include/perf/cpumap.h | 3 +- tools/perf/util/cpumap.c | 66 +++++++++++++++++++--------- tools/perf/util/env.c | 2 +- 4 files changed, 53 insertions(+), 26 deletions(-) diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c index fcc47214062a..4454a5987570 100644 --- a/tools/lib/perf/cpumap.c +++ b/tools/lib/perf/cpumap.c @@ -185,7 +185,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list) while (isdigit(*cpu_list)) { p = NULL; start_cpu = strtoul(cpu_list, &p, 0); - if (start_cpu >= INT_MAX + if (start_cpu >= INT16_MAX || (*p != '\0' && *p != ',' && *p != '-' && *p != '\n')) goto invalid; @@ -194,7 +194,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list) p = NULL; end_cpu = strtoul(cpu_list, &p, 0); - if (end_cpu >= INT_MAX || (*p != '\0' && *p != ',' && *p != '\n')) + if (end_cpu >= INT16_MAX || (*p != '\0' && *p != ',' && *p != '\n')) goto invalid; if (end_cpu < start_cpu) @@ -209,7 +209,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list) for (; start_cpu <= end_cpu; start_cpu++) { /* check for duplicates */ for (i = 0; i < nr_cpus; i++) - if (tmp_cpus[i].cpu == (int)start_cpu) + if (tmp_cpus[i].cpu == (int16_t)start_cpu) goto invalid; if (nr_cpus == max_entries) { @@ -219,7 +219,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list) goto invalid; tmp_cpus = tmp; } - tmp_cpus[nr_cpus++].cpu = (int)start_cpu; + tmp_cpus[nr_cpus++].cpu = (int16_t)start_cpu; } if (*p) ++p; diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h index 188a667babc6..8c1ab0f9194e 100644 --- a/tools/lib/perf/include/perf/cpumap.h +++ b/tools/lib/perf/include/perf/cpumap.h @@ -4,10 +4,11 @@ #include #include +#include /** A wrapper around a CPU to avoid confusion with the perf_cpu_map's map's indices. */ struct perf_cpu { - int cpu; + int16_t cpu; }; struct perf_cache { diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c index 5c329ad614e9..9bc5e0370234 100644 --- a/tools/perf/util/cpumap.c +++ b/tools/perf/util/cpumap.c @@ -67,19 +67,23 @@ static struct perf_cpu_map *cpu_map__from_entries(const struct perf_record_cpu_m struct perf_cpu_map *map; map = perf_cpu_map__empty_new(data->cpus_data.nr); - if (map) { - unsigned i; + if (!map) + return NULL; - for (i = 0; i < data->cpus_data.nr; i++) { - /* - * Special treatment for -1, which is not real cpu number, - * and we need to use (int) -1 to initialize map[i], - * otherwise it would become 65535. - */ - if (data->cpus_data.cpu[i] == (u16) -1) - RC_CHK_ACCESS(map)->map[i].cpu = -1; - else - RC_CHK_ACCESS(map)->map[i].cpu = (int) data->cpus_data.cpu[i]; + for (unsigned int i = 0; i < data->cpus_data.nr; i++) { + /* + * Special treatment for -1, which is not real cpu number, + * and we need to use (int) -1 to initialize map[i], + * otherwise it would become 65535. + */ + if (data->cpus_data.cpu[i] == (u16) -1) { + RC_CHK_ACCESS(map)->map[i].cpu = -1; + } else if (data->cpus_data.cpu[i] < INT16_MAX) { + RC_CHK_ACCESS(map)->map[i].cpu = (int16_t) data->cpus_data.cpu[i]; + } else { + pr_err("Invalid cpumap entry %u\n", data->cpus_data.cpu[i]); + perf_cpu_map__put(map); + return NULL; } } @@ -106,8 +110,15 @@ static struct perf_cpu_map *cpu_map__from_mask(const struct perf_record_cpu_map_ int cpu; perf_record_cpu_map_data__read_one_mask(data, i, local_copy); - for_each_set_bit(cpu, local_copy, 64) - RC_CHK_ACCESS(map)->map[j++].cpu = cpu + cpus_per_i; + for_each_set_bit(cpu, local_copy, 64) { + if (cpu + cpus_per_i < INT16_MAX) { + RC_CHK_ACCESS(map)->map[j++].cpu = cpu + cpus_per_i; + } else { + pr_err("Invalid cpumap entry %d\n", cpu + cpus_per_i); + perf_cpu_map__put(map); + return NULL; + } + } } return map; @@ -127,8 +138,15 @@ static struct perf_cpu_map *cpu_map__from_range(const struct perf_record_cpu_map RC_CHK_ACCESS(map)->map[i++].cpu = -1; for (int cpu = data->range_cpu_data.start_cpu; cpu <= data->range_cpu_data.end_cpu; - i++, cpu++) - RC_CHK_ACCESS(map)->map[i].cpu = cpu; + i++, cpu++) { + if (cpu < INT16_MAX) { + RC_CHK_ACCESS(map)->map[i].cpu = cpu; + } else { + pr_err("Invalid cpumap entry %d\n", cpu); + perf_cpu_map__put(map); + return NULL; + } + } return map; } @@ -427,7 +445,7 @@ static void set_max_cpu_num(void) { const char *mnt; char path[PATH_MAX]; - int ret = -1; + int max, ret = -1; /* set up default */ max_cpu_num.cpu = 4096; @@ -444,10 +462,12 @@ static void set_max_cpu_num(void) goto out; } - ret = get_max_num(path, &max_cpu_num.cpu); + ret = get_max_num(path, &max); if (ret) goto out; + max_cpu_num.cpu = max; + /* get the highest present cpu number for a sparse allocation */ ret = snprintf(path, PATH_MAX, "%s/devices/system/cpu/present", mnt); if (ret >= PATH_MAX) { @@ -455,8 +475,14 @@ static void set_max_cpu_num(void) goto out; } - ret = get_max_num(path, &max_present_cpu_num.cpu); + ret = get_max_num(path, &max); + if (!ret && max > INT16_MAX) { + pr_err("Read out of bounds max cpus of %d\n", max); + ret = -1; + } + if (!ret) + max_present_cpu_num.cpu = (int16_t)max; out: if (ret) pr_err("Failed to read max cpus, using default of %d\n", max_cpu_num.cpu); @@ -606,7 +632,7 @@ size_t cpu_map__snprint(struct perf_cpu_map *map, char *buf, size_t size) #define COMMA first ? "" : "," for (i = 0; i < perf_cpu_map__nr(map) + 1; i++) { - struct perf_cpu cpu = { .cpu = INT_MAX }; + struct perf_cpu cpu = { .cpu = INT16_MAX }; bool last = i == perf_cpu_map__nr(map); if (!last) diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c index cae4f6d63318..36411749e007 100644 --- a/tools/perf/util/env.c +++ b/tools/perf/util/env.c @@ -543,7 +543,7 @@ int perf_env__numa_node(struct perf_env *env, struct perf_cpu cpu) for (i = 0; i < env->nr_numa_nodes; i++) { nn = &env->numa_nodes[i]; - nr = max(nr, perf_cpu_map__max(nn->map).cpu); + nr = max(nr, (int)perf_cpu_map__max(nn->map).cpu); } nr++;