perf buildid: add perfconfig option to specify buildid cache dir

This patch adds the ability to specify an alternate directory to store the
buildid cache (buildids, copy of binaries). By default, it is hardcoded to
$HOME/.debug. This directory contains immutable data. The layout of the
directory is such that no conflicts in filenames are possible. A modification
in a file, yields a different buildid and thus a different location in the
subdir hierarchy.

You may want to put the buildid cache elsewhere because of disk space
limitation or simply to share the cache between users. It is also useful for
remote collect vs. local analysis of profiles.

This patch adds a new config option to the perfconfig file.  Under the tag
'buildid', there is a dir option. For instance, if you have:

$ cat /etc/perfconfig
[buildid]
dir = /var/cache/perf-buildid

All buildids and binaries are be saved in the directory specified. The perf
record, buildid-list, buildid-cache, report, annotate, and archive commands
will it to pull information out.

The option can be set in the system-wide perfconfig file or in the
$HOME/.perfconfig file.

Cc: David S. Miller <davem@davemloft.net>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4c055fb7.df0ce30a.5f0d.ffffae52@mx.google.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-buildid-cache.c

@@ -78,8 +78,7 @@ static int __cmd_buildid_cache(void)
 	struct str_node *pos;
 	char debugdir[PATH_MAX];
 
-	snprintf(debugdir, sizeof(debugdir), "%s/%s", getenv("HOME"),
-		 DEBUG_CACHE_DIR);
+	snprintf(debugdir, sizeof(debugdir), "%s", buildid_dir);
 
 	if (add_name_list_str) {
 		list = strlist__new(true, add_name_list_str);

tools/perf/perf-archive.sh

@@ -7,7 +7,17 @@ if [ $# -ne 0 ] ; then
 	PERF_DATA=$1
 fi
 
-DEBUGDIR=~/.debug/
+#
+# PERF_BUILDID_DIR environment variable set by perf
+# path to buildid directory, default to $HOME/.debug
+#
+if [ -z $PERF_BUILDID_DIR ]; then
+	PERF_BUILDID_DIR=~/.debug/
+else
+        # append / to make substitutions work
+        PERF_BUILDID_DIR=$PERF_BUILDID_DIR/
+fi
+
 BUILDIDS=$(mktemp /tmp/perf-archive-buildids.XXXXXX)
 NOBUILDID=0000000000000000000000000000000000000000
 
@@ -22,13 +32,13 @@ MANIFEST=$(mktemp /tmp/perf-archive-manifest.XXXXXX)
 
 cut -d ' ' -f 1 $BUILDIDS | \
 while read build_id ; do
-	linkname=$DEBUGDIR.build-id/${build_id:0:2}/${build_id:2}
+	linkname=$PERF_BUILDID_DIR.build-id/${build_id:0:2}/${build_id:2}
 	filename=$(readlink -f $linkname)
-	echo ${linkname#$DEBUGDIR} >> $MANIFEST
-	echo ${filename#$DEBUGDIR} >> $MANIFEST
+	echo ${linkname#$PERF_BUILDID_DIR} >> $MANIFEST
+	echo ${filename#$PERF_BUILDID_DIR} >> $MANIFEST
 done
 
-tar cfj $PERF_DATA.tar.bz2 -C $DEBUGDIR -T $MANIFEST
+tar cfj $PERF_DATA.tar.bz2 -C $PERF_BUILDID_DIR -T $MANIFEST
 rm -f $MANIFEST $BUILDIDS
 echo -e "Now please run:\n"
 echo -e "$ tar xvf $PERF_DATA.tar.bz2 -C ~/.debug\n"

tools/perf/perf.c

@@ -458,6 +458,8 @@ int main(int argc, const char **argv)
 	handle_options(&argv, &argc, NULL);
 	commit_pager_choice();
 	set_debugfs_path();
+	set_buildid_dir();
+
 	if (argc > 0) {
 		if (!prefixcmp(argv[0], "--"))
 			argv[0] += 2;

tools/perf/util/build-id.c

@@ -43,19 +43,17 @@ struct perf_event_ops build_id__mark_dso_hit_ops = {
 char *dso__build_id_filename(struct dso *self, char *bf, size_t size)
 {
 	char build_id_hex[BUILD_ID_SIZE * 2 + 1];
-	const char *home;
 
 	if (!self->has_build_id)
 		return NULL;
 
 	build_id__sprintf(self->build_id, sizeof(self->build_id), build_id_hex);
-	home = getenv("HOME");
 	if (bf == NULL) {
-		if (asprintf(&bf, "%s/%s/.build-id/%.2s/%s", home,
-			     DEBUG_CACHE_DIR, build_id_hex, build_id_hex + 2) < 0)
+		if (asprintf(&bf, "%s/.build-id/%.2s/%s", buildid_dir,
+			     build_id_hex, build_id_hex + 2) < 0)
 			return NULL;
 	} else
-		snprintf(bf, size, "%s/%s/.build-id/%.2s/%s", home,
-			 DEBUG_CACHE_DIR, build_id_hex, build_id_hex + 2);
+		snprintf(bf, size, "%s/.build-id/%.2s/%s", buildid_dir,
+			 build_id_hex, build_id_hex + 2);
 	return bf;
 }

tools/perf/util/cache.h

@@ -23,6 +23,7 @@ extern int perf_config(config_fn_t fn, void *);
 extern int perf_config_int(const char *, const char *);
 extern int perf_config_bool(const char *, const char *);
 extern int config_error_nonbool(const char *);
+extern const char *perf_config_dirname(const char *, const char *);
 
 /* pager.c */
 extern void setup_pager(void);

tools/perf/util/config.c

@@ -11,6 +11,11 @@
 
 #define MAXNAME (256)
 
+#define DEBUG_CACHE_DIR ".debug"
+
+
+char buildid_dir[MAXPATHLEN]; /* root dir for buildid, binary cache */
+
 static FILE *config_file;
 static const char *config_file_name;
 static int config_linenr;
@@ -127,7 +132,7 @@ static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
 			break;
 		if (!iskeychar(c))
 			break;
-		name[len++] = tolower(c);
+		name[len++] = c;
 		if (len >= MAXNAME)
 			return -1;
 	}
@@ -327,6 +332,13 @@ int perf_config_bool(const char *name, const char *value)
 	return !!perf_config_bool_or_int(name, value, &discard);
 }
 
+const char *perf_config_dirname(const char *name, const char *value)
+{
+	if (!name)
+		return NULL;
+	return value;
+}
+
 static int perf_default_core_config(const char *var __used, const char *value __used)
 {
 	/* Add other config variables here and to Documentation/config.txt. */
@@ -428,3 +440,53 @@ int config_error_nonbool(const char *var)
 {
 	return error("Missing value for '%s'", var);
 }
+
+struct buildid_dir_config {
+	char *dir;
+};
+
+static int buildid_dir_command_config(const char *var, const char *value,
+				      void *data)
+{
+	struct buildid_dir_config *c = data;
+	const char *v;
+
+	/* same dir for all commands */
+	if (!prefixcmp(var, "buildid.") && !strcmp(var + 8, "dir")) {
+		v = perf_config_dirname(var, value);
+		if (!v)
+			return -1;
+		strncpy(c->dir, v, MAXPATHLEN-1);
+		c->dir[MAXPATHLEN-1] = '\0';
+	}
+	return 0;
+}
+
+static void check_buildid_dir_config(void)
+{
+	struct buildid_dir_config c;
+	c.dir = buildid_dir;
+	perf_config(buildid_dir_command_config, &c);
+}
+
+void set_buildid_dir(void)
+{
+	buildid_dir[0] = '\0';
+
+	/* try config file */
+	check_buildid_dir_config();
+
+	/* default to $HOME/.debug */
+	if (buildid_dir[0] == '\0') {
+		char *v = getenv("HOME");
+		if (v) {
+			snprintf(buildid_dir, MAXPATHLEN-1, "%s/%s",
+				 v, DEBUG_CACHE_DIR);
+		} else {
+			strncpy(buildid_dir, DEBUG_CACHE_DIR, MAXPATHLEN-1);
+		}
+		buildid_dir[MAXPATHLEN-1] = '\0';
+	}
+	/* for communicating with external commands */
+	setenv("PERF_BUILDID_DIR", buildid_dir, 1);
+}

tools/perf/util/header.c

@@ -385,8 +385,7 @@ static int perf_session__cache_build_ids(struct perf_session *self)
 	int ret;
 	char debugdir[PATH_MAX];
 
-	snprintf(debugdir, sizeof(debugdir), "%s/%s", getenv("HOME"),
-		 DEBUG_CACHE_DIR);
+	snprintf(debugdir, sizeof(debugdir), "%s", buildid_dir);
 
 	if (mkdir(debugdir, 0755) != 0 && errno != EEXIST)
 		return -1;

tools/perf/util/symbol.h

@@ -9,8 +9,6 @@
 #include <linux/rbtree.h>
 #include <stdio.h>
 
-#define DEBUG_CACHE_DIR ".debug"
-
 #ifdef HAVE_CPLUS_DEMANGLE
 extern char *cplus_demangle(const char *, int);
 

tools/perf/util/util.h

@@ -89,6 +89,7 @@
 
 extern const char *graph_line;
 extern const char *graph_dotted_line;
+extern char buildid_dir[];
 
 /* On most systems <limits.h> would have given us this, but
  * not on some systems (e.g. GNU/Hurd).
@@ -152,6 +153,7 @@ extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)))
 extern void set_die_routine(void (*routine)(const char *err, va_list params) NORETURN);
 
 extern int prefixcmp(const char *str, const char *prefix);
+extern void set_buildid_dir(void);
 
 static inline const char *skip_prefix(const char *str, const char *prefix)
 {