perf header: Fix false warning when there are no duplicate cache entries (28707826) · Commits · 戴 / test

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>

tools/perf/util/header.c

+6 −15

Original line number	Diff line number	Diff line
		@@ -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;

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