From 28707826877f84bce0977845ea529cbdd08e4e8d Mon Sep 17 00:00:00 2001 From: Michael Petlan Date: Sun, 8 Dec 2019 17:20:56 +0100 Subject: perf header: Fix false warning when there are no duplicate cache entries Before this patch, perf expected that there might be NPROC*4 unique cache entries at max, however, it also expected that some of them would be shared and/or of the same size, thus the final number of entries would be reduced to be lower than NPROC*4. In case the number of entries hadn't been reduced (was NPROC*4), the warning was printed. However, some systems might have unusual cache topology, such as the following two-processor KVM guest: cpu level shared_cpu_list size 0 1 0 32K 0 1 0 64K 0 2 0 512K 0 3 0 8192K 1 1 1 32K 1 1 1 64K 1 2 1 512K 1 3 1 8192K This KVM guest has 8 (NPROC*4) unique cache entries, which used to make perf printing the message, although there actually aren't "way too many cpu caches". v2: Removing unused argument. v3: Unifying the way we obtain number of cpus. v4: Removed '& UINT_MAX' construct which is redundant. Signed-off-by: Michael Petlan Acked-by: Jiri Olsa LPU-Reference: 20191208162056.20772-1-mpetlan@redhat.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/header.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) (limited to 'tools/perf/util/header.c') diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 4d39a75551a0..93ad27830e2b 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1089,21 +1089,18 @@ static void cpu_cache_level__fprintf(FILE *out, struct cpu_cache_level *c) fprintf(out, "L%d %-15s %8s [%s]\n", c->level, c->type, c->size, c->map); } -static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp) +#define MAX_CACHE_LVL 4 + +static int build_caches(struct cpu_cache_level caches[], u32 *cntp) { u32 i, cnt = 0; - long ncpus; u32 nr, cpu; u16 level; - ncpus = sysconf(_SC_NPROCESSORS_CONF); - if (ncpus < 0) - return -1; - - nr = (u32)(ncpus & UINT_MAX); + nr = cpu__max_cpu(); for (cpu = 0; cpu < nr; cpu++) { - for (level = 0; level < 10; level++) { + for (level = 0; level < MAX_CACHE_LVL; level++) { struct cpu_cache_level c; int err; @@ -1123,18 +1120,12 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp) caches[cnt++] = c; else cpu_cache_level__free(&c); - - if (WARN_ONCE(cnt == size, "way too many cpu caches..")) - goto out; } } - out: *cntp = cnt; return 0; } -#define MAX_CACHE_LVL 4 - static int write_cache(struct feat_fd *ff, struct evlist *evlist __maybe_unused) { @@ -1143,7 +1134,7 @@ static int write_cache(struct feat_fd *ff, u32 cnt = 0, i, version = 1; int ret; - ret = build_caches(caches, max_caches, &cnt); + ret = build_caches(caches, &cnt); if (ret) goto out; -- cgit v1.2.3-59-g8ed1b