[PATCH v3] perf mem: enable sampling loads and stores simultaneously

[Stephane Eranian]

This patch modifies perf mem to default to sampling loads
and stores simultaneously. It could only do one or the other
before yet there was no hardware restriction preventing
simultaneous collection. With this patch, one run is sufficient
to collect both.

It is still possible to sample only loads or stores by using the
-t option:
 $ perf mem -t load rec
 $ perf mem -t load rep
Or
 $ perf mem -t store rec
 $ perf mem -t store rep

The perf report TUI will show one event at a time. The store
output will contain a Weight column which will be empty.

In V2, we updated the man pages to reflect the change and
also simplify the initialization of the argv vector passed
to the cmd_*() functions as per LKML feedback.

In V3, we fixed typos in the changelog.

Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
---
 tools/perf/Documentation/perf-mem.txt |   9 +--
 tools/perf/builtin-mem.c              | 123 +++++++++++++++++++++++++++-------
 2 files changed, 105 insertions(+), 27 deletions(-)

diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt
index 1d78a40..43310d8 100644
--- a/tools/perf/Documentation/perf-mem.txt
+++ b/tools/perf/Documentation/perf-mem.txt
@@ -12,11 +12,12 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-"perf mem -t <TYPE> record" runs a command and gathers memory operation data
+"perf mem record" runs a command and gathers memory operation data
 from it, into perf.data. Perf record options are accepted and are passed through.
 
-"perf mem -t <TYPE> report" displays the result. It invokes perf report with the
-right set of options to display a memory access profile.
+"perf mem report" displays the result. It invokes perf report with the
+right set of options to display a memory access profile. By default, loads
+and stores are sampled. Use the -t option to limit to loads or stores.
 
 Note that on Intel systems the memory latency reported is the use-latency,
 not the pure load (or store latency). Use latency includes any pipeline
@@ -29,7 +30,7 @@ OPTIONS
 
 -t::
 --type=::
-	Select the memory operation type: load or store (default: load)
+	Select the memory operation type: load or store (default: load,store)
 
 -D::
 --dump-raw-samples=::
diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c
index 24db6ff..1eded0a 100644
--- a/tools/perf/builtin-mem.c
+++ b/tools/perf/builtin-mem.c
@@ -7,10 +7,13 @@
 #include "util/session.h"
 #include "util/data.h"
 
-#define MEM_OPERATION_LOAD	"load"
-#define MEM_OPERATION_STORE	"store"
+#define MEM_OPERATION_LOAD	0x1
+#define MEM_OPERATION_STORE	0x2
 
-static const char	*mem_operation		= MEM_OPERATION_LOAD;
+/*
+ * default to both load an store sampling
+ */
+static int mem_operation = MEM_OPERATION_LOAD | MEM_OPERATION_STORE;
 
 struct perf_mem {
 	struct perf_tool	tool;
@@ -25,26 +28,30 @@ static int __cmd_record(int argc, const char **argv)
 {
 	int rec_argc, i = 0, j;
 	const char **rec_argv;
-	char event[64];
 	int ret;
 
-	rec_argc = argc + 4;
+	rec_argc = argc + 7; /* max number of arguments */
 	rec_argv = calloc(rec_argc + 1, sizeof(char *));
 	if (!rec_argv)
 		return -1;
 
-	rec_argv[i++] = strdup("record");
-	if (!strcmp(mem_operation, MEM_OPERATION_LOAD))
-		rec_argv[i++] = strdup("-W");
-	rec_argv[i++] = strdup("-d");
-	rec_argv[i++] = strdup("-e");
+	rec_argv[i++] = "record";
 
-	if (strcmp(mem_operation, MEM_OPERATION_LOAD))
-		sprintf(event, "cpu/mem-stores/pp");
-	else
-		sprintf(event, "cpu/mem-loads/pp");
+	if (mem_operation & MEM_OPERATION_LOAD)
+		rec_argv[i++] = "-W";
+
+	rec_argv[i++] = "-d";
+
+	if (mem_operation & MEM_OPERATION_LOAD) {
+		rec_argv[i++] = "-e";
+		rec_argv[i++] = "cpu/mem-loads/pp";
+	}
+
+	if (mem_operation & MEM_OPERATION_STORE) {
+		rec_argv[i++] = "-e";
+		rec_argv[i++] = "cpu/mem-stores/pp";
+	}
 
-	rec_argv[i++] = strdup(event);
 	for (j = 1; j < argc; j++, i++)
 		rec_argv[i] = argv[j];
 
@@ -162,17 +169,17 @@ static int report_events(int argc, const char **argv, struct perf_mem *mem)
 	if (!rep_argv)
 		return -1;
 
-	rep_argv[i++] = strdup("report");
-	rep_argv[i++] = strdup("--mem-mode");
-	rep_argv[i++] = strdup("-n"); /* display number of samples */
+	rep_argv[i++] = "report";
+	rep_argv[i++] = "--mem-mode";
+	rep_argv[i++] = "-n"; /* display number of samples */
 
 	/*
 	 * there is no weight (cost) associated with stores, so don't print
 	 * the column
 	 */
-	if (strcmp(mem_operation, MEM_OPERATION_LOAD))
-		rep_argv[i++] = strdup("--sort=mem,sym,dso,symbol_daddr,"
-				       "dso_daddr,tlb,locked");
+	if (!(mem_operation & MEM_OPERATION_LOAD))
+		rep_argv[i++] = "--sort=mem,sym,dso,symbol_daddr,"
+				"dso_daddr,tlb,locked";
 
 	for (j = 1; j < argc; j++, i++)
 		rep_argv[i] = argv[j];
@@ -182,6 +189,75 @@ static int report_events(int argc, const char **argv, struct perf_mem *mem)
 	return ret;
 }
 
+struct mem_mode {
+	const char *name;
+	int mode;
+};
+
+#define MEM_OPT(n, m) \
+	{ .name = n, .mode = (m) }
+
+#define MEM_END { .name = NULL }
+
+static const struct mem_mode mem_modes[]={
+	MEM_OPT("load", MEM_OPERATION_LOAD),
+	MEM_OPT("store", MEM_OPERATION_STORE),
+	MEM_END
+};
+
+static int
+parse_mem_ops(const struct option *opt, const char *str, int unset)
+{
+	int *mode = (int *)opt->value;
+	const struct mem_mode *m;
+	char *s, *os = NULL, *p;
+	int ret = -1;
+
+	if (unset)
+		return 0;
+
+	/* str may be NULL in case no arg is passed to -t */
+	if (str) {
+		/* because str is read-only */
+		s = os = strdup(str);
+		if (!s)
+			return -1;
+
+		/* reset mode */
+		*mode = 0;
+
+		for (;;) {
+			p = strchr(s, ',');
+			if (p)
+				*p = '\0';
+
+			for (m = mem_modes; m->name; m++) {
+				if (!strcasecmp(s, m->name))
+					break;
+			}
+			if (!m->name) {
+				fprintf(stderr, "unknown sampling op %s,"
+					    " check man page\n", s);
+				goto error;
+			}
+
+			*mode |= m->mode;
+
+			if (!p)
+				break;
+
+			s = p + 1;
+		}
+	}
+	ret = 0;
+
+	if (*mode == 0)
+		*mode = MEM_OPERATION_LOAD;
+error:
+	free(os);
+	return ret;
+}
+
 int cmd_mem(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	struct stat st;
@@ -199,8 +275,9 @@ int cmd_mem(int argc, const char **argv, const char *prefix __maybe_unused)
 		.input_name		 = "perf.data",
 	};
 	const struct option mem_options[] = {
-	OPT_STRING('t', "type", &mem_operation,
-		   "type", "memory operations(load/store)"),
+	OPT_CALLBACK('t', "type", &mem_operation,
+		   "type", "memory operations(load,store) Default load,store",
+		    parse_mem_ops),
 	OPT_BOOLEAN('D', "dump-raw-samples", &mem.dump_raw,
 		    "dump raw samples in ASCII"),
 	OPT_BOOLEAN('U', "hide-unresolved", &mem.hide_unresolved,
-- 
1.9.1

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