[PATCH 0/2] perf_counter: add tracepoint support

[PATCH 0/2] perf_counter: add tracepoint support

[Jason Baron]

hi,

The following two patches build on Peter's initial tracepoint perf counter work.
The first patch, adds 'perf list' and 'perf stat' support to the perf tool. Thus,
we can specify tracepoint events as: '-e subsystem:event_name'. The second patch
looks for the debugfs filesystem in /proc/mounts, but also allows the user to
specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'

Below, I show the output of 'perf list', and 'perf stat' for a tbench run.

thanks,

-Jason


#perf list

List of pre-defined events (to be used in -e):

  cpu-cycles OR cycles                     [Hardware event]
  instructions                             [Hardware event]
  cache-references                         [Hardware event]
  cache-misses                             [Hardware event]
  branch-instructions OR branches          [Hardware event]
  branch-misses                            [Hardware event]
  bus-cycles                               [Hardware event]

  cpu-clock                                [Software event]
  task-clock                               [Software event]
  page-faults OR faults                    [Software event]
  minor-faults                             [Software event]
  major-faults                             [Software event]
  context-switches OR cs                   [Software event]
  cpu-migrations OR migrations             [Software event]

  L1-dcache-loads                          [Hardware cache event]
  L1-dcache-load-misses                    [Hardware cache event]
  L1-dcache-stores                         [Hardware cache event]
  L1-dcache-store-misses                   [Hardware cache event]
  L1-dcache-prefetches                     [Hardware cache event]
  L1-dcache-prefetch-misses                [Hardware cache event]
  L1-icache-loads                          [Hardware cache event]
  L1-icache-load-misses                    [Hardware cache event]
  L1-icache-prefetches                     [Hardware cache event]
  L1-icache-prefetch-misses                [Hardware cache event]
  LLC-loads                                [Hardware cache event]
  LLC-load-misses                          [Hardware cache event]
  LLC-stores                               [Hardware cache event]
  LLC-store-misses                         [Hardware cache event]
  LLC-prefetches                           [Hardware cache event]
  LLC-prefetch-misses                      [Hardware cache event]
  dTLB-loads                               [Hardware cache event]
  dTLB-load-misses                         [Hardware cache event]
  dTLB-stores                              [Hardware cache event]
  dTLB-store-misses                        [Hardware cache event]
  dTLB-prefetches                          [Hardware cache event]
  dTLB-prefetch-misses                     [Hardware cache event]
  iTLB-loads                               [Hardware cache event]
  iTLB-load-misses                         [Hardware cache event]
  branch-loads                             [Hardware cache event]
  branch-load-misses                       [Hardware cache event]

  rNNN                                     [raw hardware event descriptor]

  skb:kfree_skb                            [Tracepoint event]
  block:block_rq_abort                     [Tracepoint event]
  block:block_rq_insert                    [Tracepoint event]
  block:block_rq_issue                     [Tracepoint event]
  block:block_rq_requeue                   [Tracepoint event]
  block:block_rq_complete                  [Tracepoint event]
  block:block_bio_bounce                   [Tracepoint event]
  block:block_bio_complete                 [Tracepoint event]
  block:block_bio_backmerge                [Tracepoint event]
  block:block_bio_frontmerge               [Tracepoint event]
  block:block_bio_queue                    [Tracepoint event]
  block:block_getrq                        [Tracepoint event]
  block:block_sleeprq                      [Tracepoint event]
  block:block_plug                         [Tracepoint event]
  block:block_unplug_timer                 [Tracepoint event]
  block:block_unplug_io                    [Tracepoint event]
  block:block_split                        [Tracepoint event]
  block:block_remap                        [Tracepoint event]
  kmem:kmalloc                             [Tracepoint event]
  kmem:kmem_cache_alloc                    [Tracepoint event]
  kmem:kmalloc_node                        [Tracepoint event]
  kmem:kmem_cache_alloc_node               [Tracepoint event]
  kmem:kfree                               [Tracepoint event]
  kmem:kmem_cache_free                     [Tracepoint event]
  ftrace:kmem_free                         [Tracepoint event]
  ftrace:kmem_alloc                        [Tracepoint event]
  ftrace:power                             [Tracepoint event]
  ftrace:hw_branch                         [Tracepoint event]
  ftrace:branch                            [Tracepoint event]
  ftrace:print                             [Tracepoint event]
  ftrace:bprint                            [Tracepoint event]
  ftrace:user_stack                        [Tracepoint event]
  ftrace:kernel_stack                      [Tracepoint event]
  ftrace:special                           [Tracepoint event]
  ftrace:context_switch                    [Tracepoint event]
  ftrace:wakeup                            [Tracepoint event]
  ftrace:funcgraph_exit                    [Tracepoint event]
  ftrace:funcgraph_entry                   [Tracepoint event]
  ftrace:function                          [Tracepoint event]
  workqueue:workqueue_insertion            [Tracepoint event]
  workqueue:workqueue_execution            [Tracepoint event]
  workqueue:workqueue_creation             [Tracepoint event]
  workqueue:workqueue_destruction          [Tracepoint event]
  irq:irq_handler_entry                    [Tracepoint event]
  irq:irq_handler_exit                     [Tracepoint event]
  irq:softirq_entry                        [Tracepoint event]
  irq:softirq_exit                         [Tracepoint event]
  sched:sched_kthread_stop                 [Tracepoint event]
  sched:sched_kthread_stop_ret             [Tracepoint event]
  sched:sched_wait_task                    [Tracepoint event]
  sched:sched_wakeup                       [Tracepoint event]
  sched:sched_wakeup_new                   [Tracepoint event]
  sched:sched_switch                       [Tracepoint event]
  sched:sched_migrate_task                 [Tracepoint event]
  sched:sched_process_free                 [Tracepoint event]
  sched:sched_process_exit                 [Tracepoint event]
  sched:sched_process_wait                 [Tracepoint event]
  sched:sched_process_fork                 [Tracepoint event]
  sched:sched_signal_send                  [Tracepoint event]




#  perf stat  -a -e sched:sched_switch -e sched:sched_wakeup -e irq:irq_handler_entry
tbench 4

 Performance counter stats for 'tbench 4':

      194658693  sched:sched_switch
       97479295  sched:sched_wakeup
           9122  irq:irq_handler_entry

  720.171439729  seconds time elapsed


  -add support for tracepoints to the perf tool
  -add detection for debugfs mount directory

 tools/perf/perf.c              |   58 +++++++++++++-
 tools/perf/util/cache.h        |    1 +
 tools/perf/util/parse-events.c |  176 +++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/parse-events.h |    3 +
 tools/perf/util/string.h       |    3 +
 tools/perf/util/util.h         |    2 +
 6 files changed, 241 insertions(+), 2 deletions(-)

[PATCH 1/2] perf_counter: add tracepoint support to perf list, perf stat

[Jason Baron]

Add support to 'perf list' and 'perf stat' for kernel tracepoints. The
implementation creates a 'for_each_subsystem' and 'for_each_event' for
easy iteration over the tracepoints.


Signed-off-by: Jason Baron <jbaron@redhat.com>


---
 tools/perf/util/parse-events.c |  175 +++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/util.h         |    2 +
 2 files changed, 176 insertions(+), 1 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index d18c98e..5a3cd3a 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -12,6 +12,8 @@ int					nr_counters;
 
 struct perf_counter_attr		attrs[MAX_COUNTERS];
 
+static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
+
 struct event_symbol {
 	u8	type;
 	u64	config;
@@ -110,6 +112,88 @@ static unsigned long hw_cache_stat[C(MAX)] = {
  [C(BPU)]	= (CACHE_READ),
 };
 
+#define for_each_subsystem(sys_dir, sys_dirent, sys_next, file, st)	       \
+	while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next)	       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s", default_debugfs_path,	       \
+			sys_dirent.d_name) &&				       \
+	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
+	   (strcmp(sys_dirent.d_name, ".")) &&				       \
+	   (strcmp(sys_dirent.d_name, "..")))
+
+#define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next, file, st)    \
+	while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next)        \
+	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", default_debugfs_path,       \
+			sys_dirent.d_name, evt_dirent.d_name) &&	       \
+	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
+	   (strcmp(evt_dirent.d_name, ".")) &&				       \
+	   (strcmp(evt_dirent.d_name, "..")))
+
+#define MAX_EVENT_LENGTH 30
+
+static int valid_debugfs_mount(void)
+{
+	struct statfs st_fs;
+
+	if (statfs(default_debugfs_path, &st_fs) < 0)
+		return -ENOENT;
+	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+		return -ENOENT;
+	return 0;
+}
+
+static char *tracepoint_id_to_name(u64 config)
+{
+	static char tracepoint_name[2 * MAX_EVENT_LENGTH];
+	DIR *sys_dir, *evt_dir;
+	struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+	struct stat st;
+	char id_buf[4];
+	int fd;
+	u64 id;
+	char evt_path[MAXPATHLEN];
+
+	if (valid_debugfs_mount())
+		return "unkown";
+
+	sys_dir = opendir(default_debugfs_path);
+	if (!sys_dir)
+		goto cleanup;
+
+	for_each_subsystem(sys_dir, sys_dirent, sys_next, evt_path, st) {
+		evt_dir = opendir(evt_path);
+		if (!evt_dir)
+			goto cleanup;
+		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
+								evt_path, st) {
+			snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id",
+				 default_debugfs_path, sys_dirent.d_name,
+				 evt_dirent.d_name);
+			fd = open(evt_path, O_RDONLY);
+			if (fd < 0)
+				continue;
+			if (read(fd, id_buf, sizeof(id_buf)) < 0) {
+				close(fd);
+				continue;
+			}
+			close(fd);
+			id = atoll(id_buf);
+			if (id == config) {
+				closedir(evt_dir);
+				closedir(sys_dir);
+				snprintf(tracepoint_name, 2 * MAX_EVENT_LENGTH,
+					"%s:%s", sys_dirent.d_name,
+					evt_dirent.d_name);
+				return tracepoint_name;
+			}
+		}
+		closedir(evt_dir);
+	}
+
+cleanup:
+	closedir(sys_dir);
+	return "unkown";
+}
+
 static int is_cache_op_valid(u8 cache_type, u8 cache_op)
 {
 	if (hw_cache_stat[cache_type] & COP(cache_op))
@@ -177,6 +261,9 @@ char *event_name(int counter)
 			return sw_event_names[config];
 		return "unknown-software";
 
+	case PERF_TYPE_TRACEPOINT:
+		return tracepoint_id_to_name(config);
+
 	default:
 		break;
 	}
@@ -265,6 +352,53 @@ parse_generic_hw_event(const char **str, struct perf_counter_attr *attr)
 	return 1;
 }
 
+static int parse_tracepoint_event(const char **strp,
+				    struct perf_counter_attr *attr)
+{
+	const char *evt_name;
+	char sys_name[MAX_EVENT_LENGTH];
+	char id_buf[4];
+	int fd;
+	unsigned int sys_length, evt_length;
+	u64 id;
+	char evt_path[MAXPATHLEN];
+
+	if (valid_debugfs_mount())
+		return 0;
+
+	evt_name = strchr(*strp, ':');
+	if (!evt_name)
+		return 0;
+
+	sys_length = evt_name - *strp;
+	if (sys_length >= MAX_EVENT_LENGTH)
+		return 0;
+
+	strncpy(sys_name, *strp, sys_length);
+	sys_name[sys_length] = '\0';
+	evt_name = evt_name + 1;
+	evt_length = strlen(evt_name);
+	if (evt_length >= MAX_EVENT_LENGTH)
+		return 0;
+
+	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", default_debugfs_path,
+				sys_name, evt_name);
+	fd = open(evt_path, O_RDONLY);
+	if (fd < 0)
+		return 0;
+
+	if (read(fd, id_buf, sizeof(id_buf)) < 0) {
+		close(fd);
+		return 0;
+	}
+	close(fd);
+	id = atoll(id_buf);
+	attr->config = id;
+	attr->type = PERF_TYPE_TRACEPOINT;
+	*strp = evt_name + evt_length;
+	return 1;
+}
+
 static int check_events(const char *str, unsigned int i)
 {
 	int n;
@@ -374,7 +508,8 @@ parse_event_modifier(const char **strp, struct perf_counter_attr *attr)
  */
 static int parse_event_symbols(const char **str, struct perf_counter_attr *attr)
 {
-	if (!(parse_raw_event(str, attr) ||
+	if (!(parse_tracepoint_event(str, attr) ||
+	      parse_raw_event(str, attr) ||
 	      parse_numeric_event(str, attr) ||
 	      parse_symbolic_event(str, attr) ||
 	      parse_generic_hw_event(str, attr)))
@@ -423,6 +558,42 @@ static const char * const event_type_descriptors[] = {
 };
 
 /*
+ * Print the events from <debugfs_mount_point>/tracing/events
+ */
+
+static void print_tracepoint_events(void)
+{
+	DIR *sys_dir, *evt_dir;
+	struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+	struct stat st;
+	char evt_path[MAXPATHLEN];
+
+	if (valid_debugfs_mount())
+		return;
+
+	sys_dir = opendir(default_debugfs_path);
+	if (!sys_dir)
+		goto cleanup;
+
+	for_each_subsystem(sys_dir, sys_dirent, sys_next, evt_path, st) {
+		evt_dir = opendir(evt_path);
+		if (!evt_dir)
+			goto cleanup;
+		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
+								evt_path, st) {
+			snprintf(evt_path, MAXPATHLEN, "%s:%s",
+				 sys_dirent.d_name, evt_dirent.d_name);
+			fprintf(stderr, "  %-40s [%s]\n", evt_path,
+				event_type_descriptors[PERF_TYPE_TRACEPOINT+1]);
+		}
+		closedir(evt_dir);
+	}
+
+cleanup:
+	closedir(sys_dir);
+}
+
+/*
  * Print the help text for the event symbols:
  */
 void print_events(void)
@@ -472,5 +643,7 @@ void print_events(void)
 		"rNNN");
 	fprintf(stderr, "\n");
 
+	print_tracepoint_events();
+
 	exit(129);
 }
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index b4be607..68fe157 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -50,6 +50,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <sys/stat.h>
+#include <sys/statfs.h>
 #include <fcntl.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -80,6 +81,7 @@
 #include <netdb.h>
 #include <pwd.h>
 #include <inttypes.h>
+#include "../../../include/linux/magic.h"
 
 #ifndef NO_ICONV
 #include <iconv.h>
-- 
1.6.0.6

[PATCH 2/2] perf_counter: detect debugfs location

[Jason Baron]

Search for the debugfs filesystem in /proc/mounts, but also allows the user to
specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'

Signed-off-by: Jason Baron <jbaron@redhat.com>


---
 tools/perf/perf.c              |   58 +++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/cache.h        |    1 +
 tools/perf/util/parse-events.c |   25 +++++++++--------
 tools/perf/util/parse-events.h |    3 ++
 tools/perf/util/string.h       |    3 ++
 5 files changed, 77 insertions(+), 13 deletions(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index c565678..67e3da9 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -12,6 +12,8 @@
 #include "util/cache.h"
 #include "util/quote.h"
 #include "util/run-command.h"
+#include "util/parse-events.h"
+#include "util/string.h"
 
 const char perf_usage_string[] =
 	"perf [--version] [--help] COMMAND [ARGS]";
@@ -25,6 +27,8 @@ struct pager_config {
 	int val;
 };
 
+static char debugfs_mntpt[MAXPATHLEN];
+
 static int pager_command_config(const char *var, const char *value, void *data)
 {
 	struct pager_config *c = data;
@@ -56,6 +60,15 @@ static void commit_pager_choice(void) {
 	}
 }
 
+static void set_debugfs_path(void)
+{
+	char *path;
+
+	path = getenv(PERF_DEBUGFS_ENVIRONMENT);
+	snprintf(debugfs_path, MAXPATHLEN, "%s/%s", path ?: debugfs_mntpt,
+		 "tracing/events");
+}
+
 static int handle_options(const char*** argv, int* argc, int* envchanged)
 {
 	int handled = 0;
@@ -122,6 +135,22 @@ static int handle_options(const char*** argv, int* argc, int* envchanged)
 			setenv(PERF_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "--debugfs-dir")) {
+			if (*argc < 2) {
+				fprintf(stderr, "No directory given for --debugfs-dir.\n");
+				usage(perf_usage_string);
+			}
+			strncpy(debugfs_mntpt, (*argv)[1], MAXPATHLEN);
+			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			if (envchanged)
+				*envchanged = 1;
+			(*argv)++;
+			(*argc)--;
+		} else if (!prefixcmp(cmd, "--debugfs-dir=")) {
+			strncpy(debugfs_mntpt, cmd + 14, MAXPATHLEN);
+			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			if (envchanged)
+				*envchanged = 1;
 		} else {
 			fprintf(stderr, "Unknown option: %s\n", cmd);
 			usage(perf_usage_string);
@@ -228,6 +257,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 	if (use_pager == -1 && p->option & USE_PAGER)
 		use_pager = 1;
 	commit_pager_choice();
+	set_debugfs_path();
 
 	status = p->fn(argc, argv, prefix);
 	if (status)
@@ -346,6 +376,30 @@ static int run_argv(int *argcp, const char ***argv)
 	return done_alias;
 }
 
+/* mini /proc/mounts parser: searching for "^blah /mount/point debugfs" */
+static void get_debugfs_mntpt(void)
+{
+	FILE *file;
+	char fs_type[100];
+	char debugfs[MAXPATHLEN];
+
+	file = fopen("/proc/mounts", "r");
+	if (file == NULL)
+		return;
+
+	while (fscanf(file, "%*s %"
+		      STR(MAXPATHLEN)
+		      "s %99s %*s %*d %*d\n",
+		      debugfs, fs_type) == 2) {
+		if (strcmp(fs_type, "debugfs") == 0)
+			break;
+	}
+	fclose(file);
+	if (strcmp(fs_type, "debugfs") == 0) {
+		strncpy(debugfs_mntpt, debugfs, MAXPATHLEN);
+		debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+	}
+}
 
 int main(int argc, const char **argv)
 {
@@ -354,7 +408,8 @@ int main(int argc, const char **argv)
 	cmd = perf_extract_argv0_path(argv[0]);
 	if (!cmd)
 		cmd = "perf-help";
-
+	/* get debugfs mount point from /proc/mounts */
+	get_debugfs_mntpt();
 	/*
 	 * "perf-xxxx" is the same as "perf xxxx", but we obviously:
 	 *
@@ -377,6 +432,7 @@ int main(int argc, const char **argv)
 	argc--;
 	handle_options(&argv, &argc, NULL);
 	commit_pager_choice();
+	set_debugfs_path();
 	if (argc > 0) {
 		if (!prefixcmp(argv[0], "--"))
 			argv[0] += 2;
diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
index 161d5f4..4ba4b3e 100644
--- a/tools/perf/util/cache.h
+++ b/tools/perf/util/cache.h
@@ -18,6 +18,7 @@
 #define PERFATTRIBUTES_FILE ".perfattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
 #define ATTRIBUTE_MACRO_PREFIX "[attr]"
+#define PERF_DEBUGFS_ENVIRONMENT "PERF_DIR_DEBUGFS"
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 extern int perf_default_config(const char *, const char *, void *);
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 5a3cd3a..891fd03 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -5,6 +5,7 @@
 #include "parse-events.h"
 #include "exec_cmd.h"
 #include "string.h"
+#include "cache.h"
 
 extern char *strcasestr(const char *haystack, const char *needle);
 
@@ -12,8 +13,6 @@ int					nr_counters;
 
 struct perf_counter_attr		attrs[MAX_COUNTERS];
 
-static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
-
 struct event_symbol {
 	u8	type;
 	u64	config;
@@ -21,6 +20,8 @@ struct event_symbol {
 	char	*alias;
 };
 
+char debugfs_path[MAXPATHLEN];
+
 #define CHW(x) .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_##x
 #define CSW(x) .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_##x
 
@@ -114,16 +115,16 @@ static unsigned long hw_cache_stat[C(MAX)] = {
 
 #define for_each_subsystem(sys_dir, sys_dirent, sys_next, file, st)	       \
 	while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next)	       \
-	if (snprintf(file, MAXPATHLEN, "%s/%s", default_debugfs_path,	       \
-			sys_dirent.d_name) &&				       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s", debugfs_path,	       	       \
+			sys_dirent.d_name) &&		       		       \
 	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
 	   (strcmp(sys_dirent.d_name, ".")) &&				       \
 	   (strcmp(sys_dirent.d_name, "..")))
 
 #define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next, file, st)    \
 	while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next)        \
-	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", default_debugfs_path,       \
-			sys_dirent.d_name, evt_dirent.d_name) &&	       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", debugfs_path,	       \
+		     sys_dirent.d_name, evt_dirent.d_name) &&		       \
 	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
 	   (strcmp(evt_dirent.d_name, ".")) &&				       \
 	   (strcmp(evt_dirent.d_name, "..")))
@@ -134,7 +135,7 @@ static int valid_debugfs_mount(void)
 {
 	struct statfs st_fs;
 
-	if (statfs(default_debugfs_path, &st_fs) < 0)
+	if (statfs(debugfs_path, &st_fs) < 0)
 		return -ENOENT;
 	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
 		return -ENOENT;
@@ -155,7 +156,7 @@ static char *tracepoint_id_to_name(u64 config)
 	if (valid_debugfs_mount())
 		return "unkown";
 
-	sys_dir = opendir(default_debugfs_path);
+	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
 		goto cleanup;
 
@@ -166,7 +167,7 @@ static char *tracepoint_id_to_name(u64 config)
 		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
 								evt_path, st) {
 			snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id",
-				 default_debugfs_path, sys_dirent.d_name,
+				 debugfs_path, sys_dirent.d_name,
 				 evt_dirent.d_name);
 			fd = open(evt_path, O_RDONLY);
 			if (fd < 0)
@@ -381,8 +382,8 @@ static int parse_tracepoint_event(const char **strp,
 	if (evt_length >= MAX_EVENT_LENGTH)
 		return 0;
 
-	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", default_debugfs_path,
-				sys_name, evt_name);
+	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path,
+		 sys_name, evt_name);
 	fd = open(evt_path, O_RDONLY);
 	if (fd < 0)
 		return 0;
@@ -571,7 +572,7 @@ static void print_tracepoint_events(void)
 	if (valid_debugfs_mount())
 		return;
 
-	sys_dir = opendir(default_debugfs_path);
+	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
 		goto cleanup;
 
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index e3d5529..0b06da7 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -3,6 +3,8 @@
  * Parse symbolic events/counts passed in as options:
  */
 
+struct option;
+
 extern int			nr_counters;
 
 extern struct perf_counter_attr attrs[MAX_COUNTERS];
@@ -15,3 +17,4 @@ extern int parse_events(const struct option *opt, const char *str, int unset);
 
 extern void print_events(void);
 
+extern char debugfs_path[];
diff --git a/tools/perf/util/string.h b/tools/perf/util/string.h
index 3dca2f6..bf39dfa 100644
--- a/tools/perf/util/string.h
+++ b/tools/perf/util/string.h
@@ -5,4 +5,7 @@
 
 int hex2u64(const char *ptr, u64 *val);
 
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
 #endif
-- 
1.6.0.6

Re: [PATCH 2/2] perf_counter: detect debugfs location

[Ray Lee]

On Tue, Jul 21, 2009 at 9:20 AM, Jason Baron <jbaron@redhat.com> wrote:
>
> Search for the debugfs filesystem in /proc/mounts, but also allows the user to
> specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'

> -static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";

There are server systems out there that run with thousands of mounts.
It would be kinder to the users of those systems (ie, faster perf
startup) if you only went rooting around /proc/mounts if opening the
default location failed.

Re: [PATCH 2/2] perf_counter: detect debugfs location

[Steven Rostedt]

On Tue, 21 Jul 2009, Ray Lee wrote:

> On Tue, Jul 21, 2009 at 9:20 AM, Jason Baron <jbaron@redhat.com> wrote:
> >
> > Search for the debugfs filesystem in /proc/mounts, but also allows the user to
> > specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'
> 
> > -static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
> 
> There are server systems out there that run with thousands of mounts.
> It would be kinder to the users of those systems (ie, faster perf
> startup) if you only went rooting around /proc/mounts if opening the
> default location failed.

Well, those that have thousand of mounts could probably get away with 
setting PERF_DIR_DEBUGFS in /etc/profile.

But, a simple stat("/sys/kernel/debug/tracing") should be easy enough.

-- Steve

Re: [PATCH 2/2] perf_counter: detect debugfs location

[Ray Lee]

On Tue, Jul 21, 2009 at 9:44 AM, Steven Rostedt<rostedt@goodmis.org> wrote:
>
> On Tue, 21 Jul 2009, Ray Lee wrote:
>
>> On Tue, Jul 21, 2009 at 9:20 AM, Jason Baron <jbaron@redhat.com> wrote:
>> >
>> > Search for the debugfs filesystem in /proc/mounts, but also allows the user to
>> > specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'
>>
>> > -static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
>>
>> There are server systems out there that run with thousands of mounts.
>> It would be kinder to the users of those systems (ie, faster perf
>> startup) if you only went rooting around /proc/mounts if opening the
>> default location failed.
>
> Well, those that have thousand of mounts could probably get away with
> setting PERF_DIR_DEBUGFS in /etc/profile.

The intent of the patch is obviously to try to Do The Right Thing by
default. I think that's great. I just think it should DT(fast and)RT
instead.

> But, a simple stat("/sys/kernel/debug/tracing") should be easy enough.

<nod>

Re: [PATCH 2/2] perf_counter: detect debugfs location

[Jason Baron]

On Tue, Jul 21, 2009 at 10:01:40AM -0700, Ray Lee wrote:
> On Tue, Jul 21, 2009 at 9:44 AM, Steven Rostedt<rostedt@goodmis.org> wrote:
> >
> > On Tue, 21 Jul 2009, Ray Lee wrote:
> >
> >> On Tue, Jul 21, 2009 at 9:20 AM, Jason Baron <jbaron@redhat.com> wrote:
> >> >
> >> > Search for the debugfs filesystem in /proc/mounts, but also allows the user to
> >> > specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'
> >>
> >> > -static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
> >>
> >> There are server systems out there that run with thousands of mounts.
> >> It would be kinder to the users of those systems (ie, faster perf
> >> startup) if you only went rooting around /proc/mounts if opening the
> >> default location failed.
> >
> > Well, those that have thousand of mounts could probably get away with
> > setting PERF_DIR_DEBUGFS in /etc/profile.
> 
> The intent of the patch is obviously to try to Do The Right Thing by
> default. I think that's great. I just think it should DT(fast and)RT
> instead.
> 
> > But, a simple stat("/sys/kernel/debug/tracing") should be easy enough.
> 
> <nod>

agreed, that would be better. I'm also renaming the environment variable
PERF_DIR_DEBUGFS -> PERF_DEBUGFS_DIR, as Zach Brown pointed out.
Re-spun path below.

thanks,

-Jason

If "/sys/kernel/debug" is not a debugfs mount point, search for the debugfs 
filesystem in /proc/mounts, but also allows the user to specify
'--debugfs-dir=blah' or set the environment variable: 'PERF_DEBUGFS_DIR'

Signed-off-by: Jason Baron <jbaron@redhat.com>

---

 tools/perf/perf.c              |   63 +++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/cache.h        |    1 +
 tools/perf/util/parse-events.c |   33 +++++++++++----------
 tools/perf/util/parse-events.h |    5 +++
 tools/perf/util/string.h       |    3 ++
 5 files changed, 88 insertions(+), 17 deletions(-)


diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index c565678..6d5b121 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -12,6 +12,8 @@
 #include "util/cache.h"
 #include "util/quote.h"
 #include "util/run-command.h"
+#include "util/parse-events.h"
+#include "util/string.h"
 
 const char perf_usage_string[] =
 	"perf [--version] [--help] COMMAND [ARGS]";
@@ -25,6 +27,8 @@ struct pager_config {
 	int val;
 };
 
+static char debugfs_mntpt[MAXPATHLEN];
+
 static int pager_command_config(const char *var, const char *value, void *data)
 {
 	struct pager_config *c = data;
@@ -56,6 +60,15 @@ static void commit_pager_choice(void) {
 	}
 }
 
+static void set_debugfs_path(void)
+{
+	char *path;
+
+	path = getenv(PERF_DEBUGFS_ENVIRONMENT);
+	snprintf(debugfs_path, MAXPATHLEN, "%s/%s", path ?: debugfs_mntpt,
+		 "tracing/events");
+}
+
 static int handle_options(const char*** argv, int* argc, int* envchanged)
 {
 	int handled = 0;
@@ -122,6 +135,22 @@ static int handle_options(const char*** argv, int* argc, int* envchanged)
 			setenv(PERF_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "--debugfs-dir")) {
+			if (*argc < 2) {
+				fprintf(stderr, "No directory given for --debugfs-dir.\n");
+				usage(perf_usage_string);
+			}
+			strncpy(debugfs_mntpt, (*argv)[1], MAXPATHLEN);
+			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			if (envchanged)
+				*envchanged = 1;
+			(*argv)++;
+			(*argc)--;
+		} else if (!prefixcmp(cmd, "--debugfs-dir=")) {
+			strncpy(debugfs_mntpt, cmd + 14, MAXPATHLEN);
+			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			if (envchanged)
+				*envchanged = 1;
 		} else {
 			fprintf(stderr, "Unknown option: %s\n", cmd);
 			usage(perf_usage_string);
@@ -228,6 +257,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 	if (use_pager == -1 && p->option & USE_PAGER)
 		use_pager = 1;
 	commit_pager_choice();
+	set_debugfs_path();
 
 	status = p->fn(argc, argv, prefix);
 	if (status)
@@ -346,6 +376,35 @@ static int run_argv(int *argcp, const char ***argv)
 	return done_alias;
 }
 
+/* mini /proc/mounts parser: searching for "^blah /mount/point debugfs" */
+static void get_debugfs_mntpt(void)
+{
+	FILE *file;
+	char fs_type[100];
+	char debugfs[MAXPATHLEN];
+
+	if (valid_debugfs_mount("/sys/kernel/debug/") == 0) {
+		strcpy(debugfs_mntpt, "/sys/kernel/debug/");
+		return;
+	}
+
+	file = fopen("/proc/mounts", "r");
+	if (file == NULL)
+		return;
+
+	while (fscanf(file, "%*s %"
+		      STR(MAXPATHLEN)
+		      "s %99s %*s %*d %*d\n",
+		      debugfs, fs_type) == 2) {
+		if (strcmp(fs_type, "debugfs") == 0)
+			break;
+	}
+	fclose(file);
+	if (strcmp(fs_type, "debugfs") == 0) {
+		strncpy(debugfs_mntpt, debugfs, MAXPATHLEN);
+		debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+	}
+}
 
 int main(int argc, const char **argv)
 {
@@ -354,7 +413,8 @@ int main(int argc, const char **argv)
 	cmd = perf_extract_argv0_path(argv[0]);
 	if (!cmd)
 		cmd = "perf-help";
-
+	/* get debugfs mount point from /proc/mounts */
+	get_debugfs_mntpt();
 	/*
 	 * "perf-xxxx" is the same as "perf xxxx", but we obviously:
 	 *
@@ -377,6 +437,7 @@ int main(int argc, const char **argv)
 	argc--;
 	handle_options(&argv, &argc, NULL);
 	commit_pager_choice();
+	set_debugfs_path();
 	if (argc > 0) {
 		if (!prefixcmp(argv[0], "--"))
 			argv[0] += 2;
diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
index 161d5f4..4b50c41 100644
--- a/tools/perf/util/cache.h
+++ b/tools/perf/util/cache.h
@@ -18,6 +18,7 @@
 #define PERFATTRIBUTES_FILE ".perfattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
 #define ATTRIBUTE_MACRO_PREFIX "[attr]"
+#define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 extern int perf_default_config(const char *, const char *, void *);
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 5a3cd3a..7bdad8d 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -5,6 +5,7 @@
 #include "parse-events.h"
 #include "exec_cmd.h"
 #include "string.h"
+#include "cache.h"
 
 extern char *strcasestr(const char *haystack, const char *needle);
 
@@ -12,8 +13,6 @@ int					nr_counters;
 
 struct perf_counter_attr		attrs[MAX_COUNTERS];
 
-static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
-
 struct event_symbol {
 	u8	type;
 	u64	config;
@@ -21,6 +20,8 @@ struct event_symbol {
 	char	*alias;
 };
 
+char debugfs_path[MAXPATHLEN];
+
 #define CHW(x) .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_##x
 #define CSW(x) .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_##x
 
@@ -114,27 +115,27 @@ static unsigned long hw_cache_stat[C(MAX)] = {
 
 #define for_each_subsystem(sys_dir, sys_dirent, sys_next, file, st)	       \
 	while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next)	       \
-	if (snprintf(file, MAXPATHLEN, "%s/%s", default_debugfs_path,	       \
-			sys_dirent.d_name) &&				       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s", debugfs_path,	       	       \
+			sys_dirent.d_name) &&		       		       \
 	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
 	   (strcmp(sys_dirent.d_name, ".")) &&				       \
 	   (strcmp(sys_dirent.d_name, "..")))
 
 #define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next, file, st)    \
 	while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next)        \
-	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", default_debugfs_path,       \
-			sys_dirent.d_name, evt_dirent.d_name) &&	       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", debugfs_path,	       \
+		     sys_dirent.d_name, evt_dirent.d_name) &&		       \
 	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
 	   (strcmp(evt_dirent.d_name, ".")) &&				       \
 	   (strcmp(evt_dirent.d_name, "..")))
 
 #define MAX_EVENT_LENGTH 30
 
-static int valid_debugfs_mount(void)
+int valid_debugfs_mount(const char *debugfs)
 {
 	struct statfs st_fs;
 
-	if (statfs(default_debugfs_path, &st_fs) < 0)
+	if (statfs(debugfs, &st_fs) < 0)
 		return -ENOENT;
 	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
 		return -ENOENT;
@@ -152,10 +153,10 @@ static char *tracepoint_id_to_name(u64 config)
 	u64 id;
 	char evt_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount())
+	if (valid_debugfs_mount(debugfs_path))
 		return "unkown";
 
-	sys_dir = opendir(default_debugfs_path);
+	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
 		goto cleanup;
 
@@ -166,7 +167,7 @@ static char *tracepoint_id_to_name(u64 config)
 		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
 								evt_path, st) {
 			snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id",
-				 default_debugfs_path, sys_dirent.d_name,
+				 debugfs_path, sys_dirent.d_name,
 				 evt_dirent.d_name);
 			fd = open(evt_path, O_RDONLY);
 			if (fd < 0)
@@ -363,7 +364,7 @@ static int parse_tracepoint_event(const char **strp,
 	u64 id;
 	char evt_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount())
+	if (valid_debugfs_mount(debugfs_path))
 		return 0;
 
 	evt_name = strchr(*strp, ':');
@@ -381,8 +382,8 @@ static int parse_tracepoint_event(const char **strp,
 	if (evt_length >= MAX_EVENT_LENGTH)
 		return 0;
 
-	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", default_debugfs_path,
-				sys_name, evt_name);
+	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path,
+		 sys_name, evt_name);
 	fd = open(evt_path, O_RDONLY);
 	if (fd < 0)
 		return 0;
@@ -568,10 +569,10 @@ static void print_tracepoint_events(void)
 	struct stat st;
 	char evt_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount())
+	if (valid_debugfs_mount(debugfs_path))
 		return;
 
-	sys_dir = opendir(default_debugfs_path);
+	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
 		goto cleanup;
 
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index e3d5529..1ea5d09 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -3,6 +3,8 @@
  * Parse symbolic events/counts passed in as options:
  */
 
+struct option;
+
 extern int			nr_counters;
 
 extern struct perf_counter_attr attrs[MAX_COUNTERS];
@@ -15,3 +17,6 @@ extern int parse_events(const struct option *opt, const char *str, int unset);
 
 extern void print_events(void);
 
+extern char debugfs_path[];
+extern int valid_debugfs_mount(const char *debugfs);
+
diff --git a/tools/perf/util/string.h b/tools/perf/util/string.h
index 3dca2f6..bf39dfa 100644
--- a/tools/perf/util/string.h
+++ b/tools/perf/util/string.h
@@ -5,4 +5,7 @@
 
 int hex2u64(const char *ptr, u64 *val);
 
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
 #endif

Re: [PATCH 2/2] perf_counter: detect debugfs location

[Peter Zijlstra]

I queued the below.

Thanks Jason!

---
Subject: perf_counter: Detect debugfs location
From: Jason Baron <jbaron@redhat.com>
Date: Tue, 21 Jul 2009 14:16:29 -0400

If "/sys/kernel/debug" is not a debugfs mount point, search for the debugfs
filesystem in /proc/mounts, but also allows the user to specify
'--debugfs-dir=blah' or set the environment variable: 'PERF_DEBUGFS_DIR'

Signed-off-by: Jason Baron <jbaron@redhat.com>
[ also made it probe "/debug" by default ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090721181629.GA3094@redhat.com>
---
 tools/perf/perf.c              |   77 ++++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/cache.h        |    1 
 tools/perf/util/parse-events.c |   33 +++++++++--------
 tools/perf/util/parse-events.h |    5 ++
 tools/perf/util/string.h       |    3 +
 5 files changed, 102 insertions(+), 17 deletions(-)

Index: linux-2.6/tools/perf/perf.c
===================================================================
--- linux-2.6.orig/tools/perf/perf.c
+++ linux-2.6/tools/perf/perf.c
@@ -12,6 +12,8 @@
 #include "util/cache.h"
 #include "util/quote.h"
 #include "util/run-command.h"
+#include "util/parse-events.h"
+#include "util/string.h"
 
 const char perf_usage_string[] =
 	"perf [--version] [--help] COMMAND [ARGS]";
@@ -25,6 +27,8 @@ struct pager_config {
 	int val;
 };
 
+static char debugfs_mntpt[MAXPATHLEN];
+
 static int pager_command_config(const char *var, const char *value, void *data)
 {
 	struct pager_config *c = data;
@@ -56,6 +60,15 @@ static void commit_pager_choice(void) {
 	}
 }
 
+static void set_debugfs_path(void)
+{
+	char *path;
+
+	path = getenv(PERF_DEBUGFS_ENVIRONMENT);
+	snprintf(debugfs_path, MAXPATHLEN, "%s/%s", path ?: debugfs_mntpt,
+		 "tracing/events");
+}
+
 static int handle_options(const char*** argv, int* argc, int* envchanged)
 {
 	int handled = 0;
@@ -122,6 +135,22 @@ static int handle_options(const char*** 
 			setenv(PERF_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "--debugfs-dir")) {
+			if (*argc < 2) {
+				fprintf(stderr, "No directory given for --debugfs-dir.\n");
+				usage(perf_usage_string);
+			}
+			strncpy(debugfs_mntpt, (*argv)[1], MAXPATHLEN);
+			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			if (envchanged)
+				*envchanged = 1;
+			(*argv)++;
+			(*argc)--;
+		} else if (!prefixcmp(cmd, "--debugfs-dir=")) {
+			strncpy(debugfs_mntpt, cmd + 14, MAXPATHLEN);
+			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			if (envchanged)
+				*envchanged = 1;
 		} else {
 			fprintf(stderr, "Unknown option: %s\n", cmd);
 			usage(perf_usage_string);
@@ -228,6 +257,7 @@ static int run_builtin(struct cmd_struct
 	if (use_pager == -1 && p->option & USE_PAGER)
 		use_pager = 1;
 	commit_pager_choice();
+	set_debugfs_path();
 
 	status = p->fn(argc, argv, prefix);
 	if (status)
@@ -346,6 +376,49 @@ static int run_argv(int *argcp, const ch
 	return done_alias;
 }
 
+/* mini /proc/mounts parser: searching for "^blah /mount/point debugfs" */
+static void get_debugfs_mntpt(void)
+{
+	FILE *file;
+	char fs_type[100];
+	char debugfs[MAXPATHLEN];
+
+	/*
+	 * try the standard location
+	 */
+	if (valid_debugfs_mount("/sys/kernel/debug/") == 0) {
+		strcpy(debugfs_mntpt, "/sys/kernel/debug/");
+		return;
+	}
+
+	/*
+	 * try the sane location
+	 */
+	if (valid_debugfs_mount("/debug/") == 0) {
+		strcpy(debugfs_mntpt, "/debug/");
+		return;
+	}
+
+	/*
+	 * give up and parse /proc/mounts
+	 */
+	file = fopen("/proc/mounts", "r");
+	if (file == NULL)
+		return;
+
+	while (fscanf(file, "%*s %"
+		      STR(MAXPATHLEN)
+		      "s %99s %*s %*d %*d\n",
+		      debugfs, fs_type) == 2) {
+		if (strcmp(fs_type, "debugfs") == 0)
+			break;
+	}
+	fclose(file);
+	if (strcmp(fs_type, "debugfs") == 0) {
+		strncpy(debugfs_mntpt, debugfs, MAXPATHLEN);
+		debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+	}
+}
 
 int main(int argc, const char **argv)
 {
@@ -354,7 +427,8 @@ int main(int argc, const char **argv)
 	cmd = perf_extract_argv0_path(argv[0]);
 	if (!cmd)
 		cmd = "perf-help";
-
+	/* get debugfs mount point from /proc/mounts */
+	get_debugfs_mntpt();
 	/*
 	 * "perf-xxxx" is the same as "perf xxxx", but we obviously:
 	 *
@@ -377,6 +451,7 @@ int main(int argc, const char **argv)
 	argc--;
 	handle_options(&argv, &argc, NULL);
 	commit_pager_choice();
+	set_debugfs_path();
 	if (argc > 0) {
 		if (!prefixcmp(argv[0], "--"))
 			argv[0] += 2;
Index: linux-2.6/tools/perf/util/cache.h
===================================================================
--- linux-2.6.orig/tools/perf/util/cache.h
+++ linux-2.6/tools/perf/util/cache.h
@@ -18,6 +18,7 @@
 #define PERFATTRIBUTES_FILE ".perfattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
 #define ATTRIBUTE_MACRO_PREFIX "[attr]"
+#define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 extern int perf_default_config(const char *, const char *, void *);
Index: linux-2.6/tools/perf/util/parse-events.c
===================================================================
--- linux-2.6.orig/tools/perf/util/parse-events.c
+++ linux-2.6/tools/perf/util/parse-events.c
@@ -5,6 +5,7 @@
 #include "parse-events.h"
 #include "exec_cmd.h"
 #include "string.h"
+#include "cache.h"
 
 extern char *strcasestr(const char *haystack, const char *needle);
 
@@ -12,8 +13,6 @@ int					nr_counters;
 
 struct perf_counter_attr		attrs[MAX_COUNTERS];
 
-static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
-
 struct event_symbol {
 	u8	type;
 	u64	config;
@@ -21,6 +20,8 @@ struct event_symbol {
 	char	*alias;
 };
 
+char debugfs_path[MAXPATHLEN];
+
 #define CHW(x) .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_##x
 #define CSW(x) .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_##x
 
@@ -114,27 +115,27 @@ static unsigned long hw_cache_stat[C(MAX
 
 #define for_each_subsystem(sys_dir, sys_dirent, sys_next, file, st)	       \
 	while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next)	       \
-	if (snprintf(file, MAXPATHLEN, "%s/%s", default_debugfs_path,	       \
-			sys_dirent.d_name) &&				       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s", debugfs_path,	       	       \
+			sys_dirent.d_name) &&		       		       \
 	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
 	   (strcmp(sys_dirent.d_name, ".")) &&				       \
 	   (strcmp(sys_dirent.d_name, "..")))
 
 #define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next, file, st)    \
 	while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next)        \
-	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", default_debugfs_path,       \
-			sys_dirent.d_name, evt_dirent.d_name) &&	       \
+	if (snprintf(file, MAXPATHLEN, "%s/%s/%s", debugfs_path,	       \
+		     sys_dirent.d_name, evt_dirent.d_name) &&		       \
 	   (!stat(file, &st)) && (S_ISDIR(st.st_mode)) &&		       \
 	   (strcmp(evt_dirent.d_name, ".")) &&				       \
 	   (strcmp(evt_dirent.d_name, "..")))
 
 #define MAX_EVENT_LENGTH 30
 
-static int valid_debugfs_mount(void)
+int valid_debugfs_mount(const char *debugfs)
 {
 	struct statfs st_fs;
 
-	if (statfs(default_debugfs_path, &st_fs) < 0)
+	if (statfs(debugfs, &st_fs) < 0)
 		return -ENOENT;
 	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
 		return -ENOENT;
@@ -152,10 +153,10 @@ static char *tracepoint_id_to_name(u64 c
 	u64 id;
 	char evt_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount())
+	if (valid_debugfs_mount(debugfs_path))
 		return "unkown";
 
-	sys_dir = opendir(default_debugfs_path);
+	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
 		goto cleanup;
 
@@ -166,7 +167,7 @@ static char *tracepoint_id_to_name(u64 c
 		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
 								evt_path, st) {
 			snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id",
-				 default_debugfs_path, sys_dirent.d_name,
+				 debugfs_path, sys_dirent.d_name,
 				 evt_dirent.d_name);
 			fd = open(evt_path, O_RDONLY);
 			if (fd < 0)
@@ -363,7 +364,7 @@ static int parse_tracepoint_event(const 
 	u64 id;
 	char evt_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount())
+	if (valid_debugfs_mount(debugfs_path))
 		return 0;
 
 	evt_name = strchr(*strp, ':');
@@ -381,8 +382,8 @@ static int parse_tracepoint_event(const 
 	if (evt_length >= MAX_EVENT_LENGTH)
 		return 0;
 
-	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", default_debugfs_path,
-				sys_name, evt_name);
+	snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path,
+		 sys_name, evt_name);
 	fd = open(evt_path, O_RDONLY);
 	if (fd < 0)
 		return 0;
@@ -568,10 +569,10 @@ static void print_tracepoint_events(void
 	struct stat st;
 	char evt_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount())
+	if (valid_debugfs_mount(debugfs_path))
 		return;
 
-	sys_dir = opendir(default_debugfs_path);
+	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
 		goto cleanup;
 
Index: linux-2.6/tools/perf/util/parse-events.h
===================================================================
--- linux-2.6.orig/tools/perf/util/parse-events.h
+++ linux-2.6/tools/perf/util/parse-events.h
@@ -3,6 +3,8 @@
  * Parse symbolic events/counts passed in as options:
  */
 
+struct option;
+
 extern int			nr_counters;
 
 extern struct perf_counter_attr attrs[MAX_COUNTERS];
@@ -15,3 +17,6 @@ extern int parse_events(const struct opt
 
 extern void print_events(void);
 
+extern char debugfs_path[];
+extern int valid_debugfs_mount(const char *debugfs);
+
Index: linux-2.6/tools/perf/util/string.h
===================================================================
--- linux-2.6.orig/tools/perf/util/string.h
+++ linux-2.6/tools/perf/util/string.h
@@ -5,4 +5,7 @@
 
 int hex2u64(const char *ptr, u64 *val);
 
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
 #endif