From: Michael Petlan mpetlan@redhat.com
[ Upstream commit 28707826877f84bce0977845ea529cbdd08e4e8d ]
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 mpetlan@redhat.com Acked-by: Jiri Olsa jolsa@redhat.com LPU-Reference: 20191208162056.20772-1-mpetlan@redhat.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/header.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-)
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index becc2d109423..d3412f2c0d18 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;