[PATCH 0/3] perf per-task-per-cpu support

[PATCH 0/3] perf per-task-per-cpu support

[Peter Zijlstra]

Its not the most elegant solution, but it does seem to work.

[PATCH 1/3] perf: Allow per-task-per-cpu counters

[Peter Zijlstra]

[-- Attachment #1: perf1.patch --]
[-- Type: text/plain, Size: 1755 bytes --]

In order to allow for per-task-per-cpu counters, useful for
scalability when profiling task hierarchies, we allow installing
events with event->cpu != -1 in task contexts.

__perf_event_sched_in() already skips events where ->cpu mis-matches
the current cpu, fix up __perf_install_in_context() and
__perf_event_enable() to also respect this filter.

This does lead to vary hard to interpret enabled/running times for
such counters, but I don't see a simple solution for that.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 kernel/perf_event.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -782,6 +782,9 @@ static void __perf_install_in_context(vo
 
 	add_event_to_ctx(event, ctx);
 
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
 	/*
 	 * Don't put the event on if it is disabled or if
 	 * it is in a group and the group isn't on.
@@ -925,6 +928,9 @@ static void __perf_event_enable(void *in
 		goto unlock;
 	__perf_event_mark_enabled(event, ctx);
 
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
 	/*
 	 * If the event is in a group and isn't the group leader,
 	 * then don't put it on unless the group is on.
@@ -1595,10 +1601,7 @@ static struct perf_event_context *find_g
 	unsigned long flags;
 	int err;
 
-	/*
-	 * If cpu is not a wildcard then this is a percpu event:
-	 */
-	if (cpu != -1) {
+	if (pid == -1 && cpu != -1) {
 		/* Must be root to operate on a CPU event: */
 		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
 			return ERR_PTR(-EACCES);

-- 

[PATCH 2/3] perf-record: Properly synchronize child creation

[Peter Zijlstra]

[-- Attachment #1: perf2.patch --]
[-- Type: text/plain, Size: 4136 bytes --]

Remove that ugly usleep and provide proper serialization between
parent and child just like perf-stat does.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 tools/perf/builtin-record.c |  111 ++++++++++++++++++++++++++++----------------
 1 file changed, 72 insertions(+), 39 deletions(-)

Index: linux-2.6/tools/perf/builtin-record.c
===================================================================
--- linux-2.6.orig/tools/perf/builtin-record.c
+++ linux-2.6/tools/perf/builtin-record.c
@@ -402,7 +402,7 @@ static void atexit_header(void)
 	perf_header__write(&session->header, output, true);
 }
 
-static int __cmd_record(int argc, const char **argv)
+static int __cmd_record(int argc __used, const char **argv)
 {
 	int i, counter;
 	struct stat st;
@@ -410,6 +410,8 @@ static int __cmd_record(int argc, const 
 	int flags;
 	int err;
 	unsigned long waking = 0;
+	int child_ready_pipe[2], go_pipe[2];
+	char buf;
 
 	page_size = sysconf(_SC_PAGE_SIZE);
 	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
@@ -420,6 +422,11 @@ static int __cmd_record(int argc, const 
 	signal(SIGCHLD, sig_handler);
 	signal(SIGINT, sig_handler);
 
+	if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) {
+		perror("failed to create pipes");
+		exit(-1);
+	}
+
 	if (!stat(output_name, &st) && st.st_size) {
 		if (!force) {
 			if (!append_file) {
@@ -476,19 +483,65 @@ static int __cmd_record(int argc, const 
 
 	atexit(atexit_header);
 
-	if (!system_wide) {
-		pid = target_pid;
-		if (pid == -1)
-			pid = getpid();
+	if (target_pid == -1) {
+		pid = fork();
+		if (pid < 0) {
+			perror("failed to fork");
+			exit(-1);
+		}
 
-		open_counters(profile_cpu, pid);
-	} else {
-		if (profile_cpu != -1) {
-			open_counters(profile_cpu, target_pid);
-		} else {
-			for (i = 0; i < nr_cpus; i++)
-				open_counters(i, target_pid);
+		if (!pid) {
+			close(child_ready_pipe[0]);
+			close(go_pipe[1]);
+			fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
+
+			/*
+			 * Do a dummy execvp to get the PLT entry resolved,
+			 * so we avoid the resolver overhead on the real
+			 * execvp call.
+			 */
+			execvp("", (char **)argv);
+
+			/*
+			 * Tell the parent we're ready to go
+			 */
+			close(child_ready_pipe[1]);
+
+			/*
+			 * Wait until the parent tells us to go.
+			 */
+			if (read(go_pipe[0], &buf, 1) == -1)
+				perror("unable to read pipe");
+
+			execvp(argv[0], (char **)argv);
+
+			perror(argv[0]);
+			exit(-1);
 		}
+
+		child_pid = pid;
+
+		if (!system_wide)
+			target_pid = pid;
+
+		close(child_ready_pipe[1]);
+		close(go_pipe[0]);
+		/*
+		 * wait for child to settle
+		 */
+		if (read(child_ready_pipe[0], &buf, 1) == -1) {
+			perror("unable to read pipe");
+			exit(-1);
+		}
+		close(child_ready_pipe[0]);
+	}
+
+
+	if (!system_wide || profile_cpu != -1) {
+		open_counters(profile_cpu, target_pid);
+	} else {
+		for (i = 0; i < nr_cpus; i++)
+			open_counters(i, target_pid);
 	}
 
 	if (file_new) {
@@ -503,31 +556,6 @@ static int __cmd_record(int argc, const 
 	else
 		event__synthesize_threads(process_synthesized_event, session);
 
-	if (target_pid == -1 && argc) {
-		pid = fork();
-		if (pid < 0)
-			die("failed to fork");
-
-		if (!pid) {
-			if (execvp(argv[0], (char **)argv)) {
-				perror(argv[0]);
-				exit(-1);
-			}
-		} else {
-			/*
-			 * Wait a bit for the execv'ed child to appear
-			 * and be updated in /proc
-			 * FIXME: Do you know a less heuristical solution?
-			 */
-			usleep(1000);
-			event__synthesize_thread(pid,
-						 process_synthesized_event,
-						 session);
-		}
-
-		child_pid = pid;
-	}
-
 	if (realtime_prio) {
 		struct sched_param param;
 
@@ -538,6 +566,11 @@ static int __cmd_record(int argc, const 
 		}
 	}
 
+	/*
+	 * Let the child rip
+	 */
+	close(go_pipe[1]);
+
 	for (;;) {
 		int hits = samples;
 
@@ -634,7 +667,7 @@ int cmd_record(int argc, const char **ar
 
 	argc = parse_options(argc, argv, options, record_usage,
 			    PARSE_OPT_STOP_AT_NON_OPTION);
-	if (!argc && target_pid == -1 && !system_wide)
+	if (!argc && target_pid == -1 && (!system_wide || profile_cpu == -1))
 		usage_with_options(record_usage, options);
 
 	symbol__init();

-- 

[PATCH 3/3] perf-record: Use per-task-per-cpu events for inherited events

[Peter Zijlstra]

[-- Attachment #1: perf3.patch --]
[-- Type: text/plain, Size: 974 bytes --]

Create events with a pid and cpu contraint for inherited events so
that we get a stream per cpu, instead of all cpus contending on a
single stream.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 tools/perf/builtin-record.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/tools/perf/builtin-record.c
===================================================================
--- linux-2.6.orig/tools/perf/builtin-record.c
+++ linux-2.6/tools/perf/builtin-record.c
@@ -278,7 +278,7 @@ static void create_counter(int counter, 
 
 	attr->mmap		= track;
 	attr->comm		= track;
-	attr->inherit		= (cpu < 0) && inherit;
+	attr->inherit		= inherit;
 	attr->disabled		= 1;
 
 try_again:
@@ -537,7 +537,7 @@ static int __cmd_record(int argc __used,
 	}
 
 
-	if (!system_wide || profile_cpu != -1) {
+	if ((!system_wide && !inherit) || profile_cpu != -1) {
 		open_counters(profile_cpu, target_pid);
 	} else {
 		for (i = 0; i < nr_cpus; i++)

-- 

[tip:perf/urgent] perf events: Allow per-task-per-cpu counters

[tip-bot for Peter Zijlstra]

Commit-ID:  f4c4176f21533e22bcc292030da72bcfa105f5b8
Gitweb:     http://git.kernel.org/tip/f4c4176f21533e22bcc292030da72bcfa105f5b8
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 16 Dec 2009 17:55:54 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 16 Dec 2009 18:30:11 +0100

perf events: Allow per-task-per-cpu counters

In order to allow for per-task-per-cpu counters, useful for
scalability when profiling task hierarchies, we allow installing
events with event->cpu != -1 in task contexts.

__perf_event_sched_in() already skips events where ->cpu
mis-matches the current cpu, fix up __perf_install_in_context()
and __perf_event_enable() to also respect this filter.

This does lead to vary hard to interpret enabled/running times
for such counters, but I don't see a simple solution for that.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: fweisbec@gmail.com
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091216165904.831451147@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/perf_event.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 0dd8e5d..2e0aaa3 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -782,6 +782,9 @@ static void __perf_install_in_context(void *info)
 
 	add_event_to_ctx(event, ctx);
 
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
 	/*
 	 * Don't put the event on if it is disabled or if
 	 * it is in a group and the group isn't on.
@@ -925,6 +928,9 @@ static void __perf_event_enable(void *info)
 		goto unlock;
 	__perf_event_mark_enabled(event, ctx);
 
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
 	/*
 	 * If the event is in a group and isn't the group leader,
 	 * then don't put it on unless the group is on.
@@ -1595,10 +1601,7 @@ static struct perf_event_context *find_get_context(pid_t pid, int cpu)
 	unsigned long flags;
 	int err;
 
-	/*
-	 * If cpu is not a wildcard then this is a percpu event:
-	 */
-	if (cpu != -1) {
+	if (pid == -1 && cpu != -1) {
 		/* Must be root to operate on a CPU event: */
 		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
 			return ERR_PTR(-EACCES);

[tip:perf/urgent] perf record: Properly synchronize child creation

[tip-bot for Peter Zijlstra]

Commit-ID:  856e96608a72412d319e498a3a7c557571f811bd
Gitweb:     http://git.kernel.org/tip/856e96608a72412d319e498a3a7c557571f811bd
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 16 Dec 2009 17:55:55 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 16 Dec 2009 18:30:12 +0100

perf record: Properly synchronize child creation

Remove that ugly usleep and provide proper serialization between
parent and child just like perf-stat does.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: fweisbec@gmail.com
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091216165904.908184135@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 tools/perf/builtin-record.c |  109 ++++++++++++++++++++++++++++---------------
 1 files changed, 71 insertions(+), 38 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 65301c5..9b7c6d8 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -402,7 +402,7 @@ static void atexit_header(void)
 	perf_header__write(&session->header, output, true);
 }
 
-static int __cmd_record(int argc, const char **argv)
+static int __cmd_record(int argc __used, const char **argv)
 {
 	int i, counter;
 	struct stat st;
@@ -410,6 +410,8 @@ static int __cmd_record(int argc, const char **argv)
 	int flags;
 	int err;
 	unsigned long waking = 0;
+	int child_ready_pipe[2], go_pipe[2];
+	char buf;
 
 	page_size = sysconf(_SC_PAGE_SIZE);
 	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
@@ -420,6 +422,11 @@ static int __cmd_record(int argc, const char **argv)
 	signal(SIGCHLD, sig_handler);
 	signal(SIGINT, sig_handler);
 
+	if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) {
+		perror("failed to create pipes");
+		exit(-1);
+	}
+
 	if (!stat(output_name, &st) && st.st_size) {
 		if (!force) {
 			if (!append_file) {
@@ -476,19 +483,65 @@ static int __cmd_record(int argc, const char **argv)
 
 	atexit(atexit_header);
 
-	if (!system_wide) {
-		pid = target_pid;
-		if (pid == -1)
-			pid = getpid();
+	if (target_pid == -1) {
+		pid = fork();
+		if (pid < 0) {
+			perror("failed to fork");
+			exit(-1);
+		}
 
-		open_counters(profile_cpu, pid);
-	} else {
-		if (profile_cpu != -1) {
-			open_counters(profile_cpu, target_pid);
-		} else {
-			for (i = 0; i < nr_cpus; i++)
-				open_counters(i, target_pid);
+		if (!pid) {
+			close(child_ready_pipe[0]);
+			close(go_pipe[1]);
+			fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
+
+			/*
+			 * Do a dummy execvp to get the PLT entry resolved,
+			 * so we avoid the resolver overhead on the real
+			 * execvp call.
+			 */
+			execvp("", (char **)argv);
+
+			/*
+			 * Tell the parent we're ready to go
+			 */
+			close(child_ready_pipe[1]);
+
+			/*
+			 * Wait until the parent tells us to go.
+			 */
+			if (read(go_pipe[0], &buf, 1) == -1)
+				perror("unable to read pipe");
+
+			execvp(argv[0], (char **)argv);
+
+			perror(argv[0]);
+			exit(-1);
 		}
+
+		child_pid = pid;
+
+		if (!system_wide)
+			target_pid = pid;
+
+		close(child_ready_pipe[1]);
+		close(go_pipe[0]);
+		/*
+		 * wait for child to settle
+		 */
+		if (read(child_ready_pipe[0], &buf, 1) == -1) {
+			perror("unable to read pipe");
+			exit(-1);
+		}
+		close(child_ready_pipe[0]);
+	}
+
+
+	if (!system_wide || profile_cpu != -1) {
+		open_counters(profile_cpu, target_pid);
+	} else {
+		for (i = 0; i < nr_cpus; i++)
+			open_counters(i, target_pid);
 	}
 
 	if (file_new) {
@@ -503,31 +556,6 @@ static int __cmd_record(int argc, const char **argv)
 	else
 		event__synthesize_threads(process_synthesized_event, session);
 
-	if (target_pid == -1 && argc) {
-		pid = fork();
-		if (pid < 0)
-			die("failed to fork");
-
-		if (!pid) {
-			if (execvp(argv[0], (char **)argv)) {
-				perror(argv[0]);
-				exit(-1);
-			}
-		} else {
-			/*
-			 * Wait a bit for the execv'ed child to appear
-			 * and be updated in /proc
-			 * FIXME: Do you know a less heuristical solution?
-			 */
-			usleep(1000);
-			event__synthesize_thread(pid,
-						 process_synthesized_event,
-						 session);
-		}
-
-		child_pid = pid;
-	}
-
 	if (realtime_prio) {
 		struct sched_param param;
 
@@ -538,6 +566,11 @@ static int __cmd_record(int argc, const char **argv)
 		}
 	}
 
+	/*
+	 * Let the child rip
+	 */
+	close(go_pipe[1]);
+
 	for (;;) {
 		int hits = samples;
 
@@ -634,7 +667,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
 
 	argc = parse_options(argc, argv, options, record_usage,
 			    PARSE_OPT_STOP_AT_NON_OPTION);
-	if (!argc && target_pid == -1 && !system_wide)
+	if (!argc && target_pid == -1 && (!system_wide || profile_cpu == -1))
 		usage_with_options(record_usage, options);
 
 	symbol__init();

[tip:perf/urgent] perf record: Use per-task-per-cpu events for inherited events

[tip-bot for Peter Zijlstra]

Commit-ID:  60ab271617cec607380099f3ed8e84916e48323b
Gitweb:     http://git.kernel.org/tip/60ab271617cec607380099f3ed8e84916e48323b
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 16 Dec 2009 17:55:56 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 16 Dec 2009 18:30:13 +0100

perf record: Use per-task-per-cpu events for inherited events

Create events with a pid and cpu contraint for inherited events
so that we get a stream per cpu, instead of all cpus contending
on a single stream.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: fweisbec@gmail.com
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091216165904.987643843@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 tools/perf/builtin-record.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 9b7c6d8..63136d0 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -278,7 +278,7 @@ static void create_counter(int counter, int cpu, pid_t pid)
 
 	attr->mmap		= track;
 	attr->comm		= track;
-	attr->inherit		= (cpu < 0) && inherit;
+	attr->inherit		= inherit;
 	attr->disabled		= 1;
 
 try_again:
@@ -537,7 +537,7 @@ static int __cmd_record(int argc __used, const char **argv)
 	}
 
 
-	if (!system_wide || profile_cpu != -1) {
+	if ((!system_wide && !inherit) || profile_cpu != -1) {
 		open_counters(profile_cpu, target_pid);
 	} else {
 		for (i = 0; i < nr_cpus; i++)