[PATCH 06/11] perf, tools: Automatically look for event file name for cpu

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

When no JSON event file is specified automatically look
for a suitable file in ~/.cache/pmu-events. A "perf download" can
automatically add files there for the current CPUs.

This does not include the actual event files with perf,
but they can be automatically downloaded instead
(implemented in the next patch)

This has the advantage that the events can be always uptodate,
because they are freshly downloaded. In oprofile we always
had problems with out of date or incomplete events files.

The event file format is per architecture, but can be
extended for other architectures.

v2: Supports XDG_CACHE_HOME and defaults to ~/.cache/pmu-events
v3: Minor updates and handle EVENTMAP.
v4: Unify with header.c. Now uses CPUID directly.
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 tools/perf/arch/x86/util/header.c | 19 ++++++++++++++++---
 tools/perf/util/jevents.c         | 40 +++++++++++++++++++++++++++++++++++++++
 tools/perf/util/jevents.h         |  1 +
 tools/perf/util/pmu.c             |  2 +-
 4 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/tools/perf/arch/x86/util/header.c b/tools/perf/arch/x86/util/header.c
index 146d12a..76e0ece 100644
--- a/tools/perf/arch/x86/util/header.c
+++ b/tools/perf/arch/x86/util/header.c
@@ -5,6 +5,7 @@
 #include <string.h>
 
 #include "../../util/header.h"
+#include "../../util/jevents.h"
 
 static inline void
 cpuid(unsigned int op, unsigned int *a, unsigned int *b, unsigned int *c,
@@ -19,8 +20,8 @@ cpuid(unsigned int op, unsigned int *a, unsigned int *b, unsigned int *c,
 			: "a" (op));
 }
 
-int
-get_cpuid(char *buffer, size_t sz)
+static int
+__get_cpuid(char *buffer, size_t sz, const char *fmt)
 {
 	unsigned int a, b, c, d, lvl;
 	int family = -1, model = -1, step = -1;
@@ -48,7 +49,7 @@ get_cpuid(char *buffer, size_t sz)
 		if (family >= 0x6)
 			model += ((a >> 16) & 0xf) << 4;
 	}
-	nb = scnprintf(buffer, sz, "%s,%u,%u,%u$", vendor, family, model, step);
+	nb = scnprintf(buffer, sz, fmt, vendor, family, model, step);
 
 	/* look for end marker to ensure the entire data fit */
 	if (strchr(buffer, '$')) {
@@ -57,3 +58,15 @@ get_cpuid(char *buffer, size_t sz)
 	}
 	return -1;
 }
+
+int get_cpuid(char *buffer, size_t sz)
+{
+	return __get_cpuid(buffer, sz, "%s,%u,%u,%u$");
+}
+
+char *get_cpu_str(void)
+{
+	char *buf = malloc(128);
+	__get_cpuid(buf, 128, "%s-%d-%X-core");
+	return buf;
+}
diff --git a/tools/perf/util/jevents.c b/tools/perf/util/jevents.c
index a23f57f..418502a 100644
--- a/tools/perf/util/jevents.c
+++ b/tools/perf/util/jevents.c
@@ -38,6 +38,44 @@
 #include "json.h"
 #include "jevents.h"
 
+__attribute__((weak)) char *get_cpu_str(void)
+{
+	return NULL;
+}
+
+static const char *json_default_name(void)
+{
+	char *cache;
+	char *idstr = get_cpu_str();
+	char *res = NULL;
+	char *home = NULL;
+	char *emap;
+
+	emap = getenv("EVENTMAP");
+	if (emap) {
+		if (access(emap, R_OK) == 0)
+			return emap;
+		if (asprintf(&idstr, "%s-core", emap) < 0)
+			return NULL;
+	}
+
+	cache = getenv("XDG_CACHE_HOME");
+	if (!cache) {
+		home = getenv("HOME");
+		if (!home || asprintf(&cache, "%s/.cache", home) < 0)
+			goto out;
+	}
+	if (cache && idstr)
+		res = mkpath("%s/pmu-events/%s.json",
+			     cache,
+			     idstr);
+	if (home)
+		free(cache);
+out:
+	free(idstr);
+	return res;
+}
+
 static void addfield(char *map, char **dst, const char *sep,
 		     const char *a, jsmntok_t *bt)
 {
@@ -170,6 +208,8 @@ int json_events(const char *fn,
 	int i, j, len;
 	char *map;
 
+	if (!fn)
+		fn = json_default_name();
 	tokens = parse_json(fn, &map, &size, &len);
 	if (!tokens)
 		return -EIO;
diff --git a/tools/perf/util/jevents.h b/tools/perf/util/jevents.h
index fbc4549..86a94dd 100644
--- a/tools/perf/util/jevents.h
+++ b/tools/perf/util/jevents.h
@@ -4,5 +4,6 @@
 int json_events(const char *fn,
 		int (*func)(void *data, char *name, char *event, char *desc),
 		void *data);
+char *get_cpu_str(void);
 
 #endif
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 9f154af..fa21319 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -433,7 +433,7 @@ static struct perf_pmu *pmu_lookup(const char *name)
 	if (pmu_aliases(name, &aliases))
 		return NULL;
 
-	if (!strcmp(name, "cpu") && json_file)
+	if (!strcmp(name, "cpu"))
 		json_events(json_file, add_alias, &aliases);
 
 	if (pmu_type(name, &type))
-- 
1.9.3

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