[PATCH v2 1/2] perf tool: Refactor comm/tgid lookup

[PATCH v2 1/2] perf tool: Refactor comm/tgid lookup

[David Ahern]

Rather than parsing /proc/pid/status file one line at a time, read
it into a buffer in one shot and search for all strings in one pass.

tgid conversion also simplified -- removing the isspace walk. As
noted by Arnaldo those are not needed for atoi == strtol calls.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
---
v2:
- removed the isspace checks on tgid string

 tools/perf/util/event.c | 72 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 44 insertions(+), 28 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index d5efa5092ce6..023dd3548a94 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -49,48 +49,64 @@ static struct perf_sample synth_sample = {
 	.period	   = 1,
 };
 
+/*
+ * Assumes that the first 4095 bytes of /proc/pid/stat contains
+ * the comm and tgid.
+ */
 static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 {
 	char filename[PATH_MAX];
-	char bf[BUFSIZ];
-	FILE *fp;
-	size_t size = 0;
+	char bf[4096];
+	int fd;
+	size_t size = 0, n;
 	pid_t tgid = -1;
+	char *nl, *name, *tgids;
 
 	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
 
-	fp = fopen(filename, "r");
-	if (fp == NULL) {
+	fd = open(filename, O_RDONLY);
+	if (fd < 0) {
 		pr_debug("couldn't open %s\n", filename);
 		return 0;
 	}
 
-	while (!comm[0] || (tgid < 0)) {
-		if (fgets(bf, sizeof(bf), fp) == NULL) {
-			pr_warning("couldn't get COMM and pgid, malformed %s\n",
-				   filename);
-			break;
-		}
+	n = read(fd, bf, sizeof(bf) - 1);
+	close(fd);
+	if (n <= 0) {
+		pr_warning("Couldn't get COMM and tgid for pid %d\n",
+			   pid);
+		return -1;
+	}
+	bf[n] = '\0';
 
-		if (memcmp(bf, "Name:", 5) == 0) {
-			char *name = bf + 5;
-			while (*name && isspace(*name))
-				++name;
-			size = strlen(name) - 1;
-			if (size >= len)
-				size = len - 1;
-			memcpy(comm, name, size);
-			comm[size] = '\0';
-
-		} else if (memcmp(bf, "Tgid:", 5) == 0) {
-			char *tgids = bf + 5;
-			while (*tgids && isspace(*tgids))
-				++tgids;
-			tgid = atoi(tgids);
-		}
+	name = strstr(bf, "Name:");
+	tgids = strstr(bf, "Tgid:");
+
+	if (name) {
+		name += 5;  /* strlen("Name:") */
+
+		while (*name && isspace(*name))
+			++name;
+
+		nl = strchr(name, '\n');
+		if (nl)
+			*nl = '\0';
+
+		size = strlen(name);
+		if (size >= len)
+			size = len - 1;
+		memcpy(comm, name, size);
+		comm[size] = '\0';
+	} else {
+		pr_debug("Name: string not found for pid %d\n", pid);
 	}
 
-	fclose(fp);
+	if (tgids) {
+		tgids += 5;  /* strlen("Tgid:") */
+		tgid = atoi(tgids);
+	} else {
+		pr_debug("Tgid: string not found for pid %d\n", pid);
+	}
 
 	return tgid;
 }
-- 
2.2.1

[PATCH v3 2/2] perf tool: Fix ppid for synthesized fork events

[David Ahern]

363b785f38 added synthesized fork events and set a thread's parent id
to itself. Since we are already processing /proc/<pid>/status the ppid
can be determined properly. Make it so.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
---
v3
- removed isspace and newline checks; added brackets per Arnaldo's comments

v2:
- removed changes to function signature for perf_event__synthesize_comm as
  noted by Jiri

 tools/perf/util/event.c | 83 +++++++++++++++++++++++++++++--------------------
 1 file changed, 50 insertions(+), 33 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 023dd3548a94..5516236df6ab 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -51,29 +51,32 @@ static struct perf_sample synth_sample = {
 
 /*
  * Assumes that the first 4095 bytes of /proc/pid/stat contains
- * the comm and tgid.
+ * the comm, tgid and ppid.
  */
-static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
+static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,
+				    pid_t *tgid, pid_t *ppid)
 {
 	char filename[PATH_MAX];
 	char bf[4096];
 	int fd;
 	size_t size = 0, n;
-	pid_t tgid = -1;
-	char *nl, *name, *tgids;
+	char *nl, *name, *tgids, *ppids;
+
+	*tgid = -1;
+	*ppid = -1;
 
 	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
 
 	fd = open(filename, O_RDONLY);
 	if (fd < 0) {
 		pr_debug("couldn't open %s\n", filename);
-		return 0;
+		return -1;
 	}
 
 	n = read(fd, bf, sizeof(bf) - 1);
 	close(fd);
 	if (n <= 0) {
-		pr_warning("Couldn't get COMM and tgid for pid %d\n",
+		pr_warning("Couldn't get COMM, tigd and ppid for pid %d\n",
 			   pid);
 		return -1;
 	}
@@ -81,6 +84,7 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 
 	name = strstr(bf, "Name:");
 	tgids = strstr(bf, "Tgid:");
+	ppids = strstr(bf, "PPid:");
 
 	if (name) {
 		name += 5;  /* strlen("Name:") */
@@ -103,32 +107,45 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 
 	if (tgids) {
 		tgids += 5;  /* strlen("Tgid:") */
-		tgid = atoi(tgids);
+		*tgid = atoi(tgids);
 	} else {
 		pr_debug("Tgid: string not found for pid %d\n", pid);
 	}
 
-	return tgid;
+	if (ppids) {
+		ppids += 5;  /* strlen("PPid:") */
+		*ppid = atoi(ppids);
+	} else {
+		pr_debug("PPid: string not found for pid %d\n", pid);
+	}
+
+	return 0;
 }
 
-static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
-					 struct machine *machine)
+static int perf_event__prepare_comm(union perf_event *event, pid_t pid,
+				    struct machine *machine,
+				    pid_t *tgid, pid_t *ppid)
 {
 	size_t size;
-	pid_t tgid;
+
+	*ppid = -1;
 
 	memset(&event->comm, 0, sizeof(event->comm));
 
-	if (machine__is_host(machine))
-		tgid = perf_event__get_comm_tgid(pid, event->comm.comm,
-						 sizeof(event->comm.comm));
-	else
-		tgid = machine->pid;
+	if (machine__is_host(machine)) {
+		if (perf_event__get_comm_ids(pid, event->comm.comm,
+					     sizeof(event->comm.comm),
+					     tgid, ppid) != 0) {
+			return -1;
+		}
+	} else {
+		*tgid = machine->pid;
+	}
 
-	if (tgid < 0)
-		goto out;
+	if (*tgid < 0)
+		return -1;
 
-	event->comm.pid = tgid;
+	event->comm.pid = *tgid;
 	event->comm.header.type = PERF_RECORD_COMM;
 
 	size = strlen(event->comm.comm) + 1;
@@ -138,8 +155,8 @@ static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
 				(sizeof(event->comm.comm) - size) +
 				machine->id_hdr_size);
 	event->comm.tid = pid;
-out:
-	return tgid;
+
+	return 0;
 }
 
 static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
@@ -147,27 +164,27 @@ static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
 					 perf_event__handler_t process,
 					 struct machine *machine)
 {
-	pid_t tgid = perf_event__prepare_comm(event, pid, machine);
+	pid_t tgid, ppid;
 
-	if (tgid == -1)
-		goto out;
+	if (perf_event__prepare_comm(event, pid, machine, &tgid, &ppid) != 0)
+		return -1;
 
 	if (process(tool, event, &synth_sample, machine) != 0)
 		return -1;
 
-out:
 	return tgid;
 }
 
 static int perf_event__synthesize_fork(struct perf_tool *tool,
-				       union perf_event *event, pid_t pid,
-				       pid_t tgid, perf_event__handler_t process,
+				       union perf_event *event,
+				       pid_t pid, pid_t tgid, pid_t ppid,
+				       perf_event__handler_t process,
 				       struct machine *machine)
 {
 	memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);
 
-	event->fork.ppid = tgid;
-	event->fork.ptid = tgid;
+	event->fork.ppid = ppid;
+	event->fork.ptid = ppid;
 	event->fork.pid  = tgid;
 	event->fork.tid  = pid;
 	event->fork.header.type = PERF_RECORD_FORK;
@@ -359,7 +376,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
 	char filename[PATH_MAX];
 	DIR *tasks;
 	struct dirent dirent, *next;
-	pid_t tgid;
+	pid_t tgid, ppid;
 
 	/* special case: only send one comm event using passed in pid */
 	if (!full) {
@@ -394,12 +411,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
 		if (*end)
 			continue;
 
-		tgid = perf_event__prepare_comm(comm_event, _pid, machine);
-		if (tgid == -1)
+		if (perf_event__prepare_comm(comm_event, _pid, machine,
+					     &tgid, &ppid) != 0)
 			return -1;
 
 		if (perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
-						process, machine) < 0)
+						ppid, process, machine) < 0)
 			return -1;
 		/*
 		 * Send the prepared comm event
-- 
2.2.1

Re: [PATCH v3 2/2] perf tool: Fix ppid for synthesized fork events

[Jiri Olsa]

On Mon, Mar 30, 2015 at 02:35:58PM -0600, David Ahern wrote:
> 363b785f38 added synthesized fork events and set a thread's parent id
> to itself. Since we are already processing /proc/<pid>/status the ppid
> can be determined properly. Make it so.
> 
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Cc: Don Zickus <dzickus@redhat.com>
> Cc: Joe Mario <jmario@redhat.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> ---
> v3
> - removed isspace and newline checks; added brackets per Arnaldo's comments
> 
> v2:
> - removed changes to function signature for perf_event__synthesize_comm as
>   noted by Jiri
> 
>  tools/perf/util/event.c | 83 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 50 insertions(+), 33 deletions(-)
> 
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 023dd3548a94..5516236df6ab 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -51,29 +51,32 @@ static struct perf_sample synth_sample = {
>  
>  /*
>   * Assumes that the first 4095 bytes of /proc/pid/stat contains
> - * the comm and tgid.
> + * the comm, tgid and ppid.
>   */
> -static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
> +static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,
> +				    pid_t *tgid, pid_t *ppid)
>  {
>  	char filename[PATH_MAX];
>  	char bf[4096];
>  	int fd;
>  	size_t size = 0, n;
> -	pid_t tgid = -1;
> -	char *nl, *name, *tgids;
> +	char *nl, *name, *tgids, *ppids;
> +
> +	*tgid = -1;
> +	*ppid = -1;
>  
>  	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
>  
>  	fd = open(filename, O_RDONLY);
>  	if (fd < 0) {
>  		pr_debug("couldn't open %s\n", filename);
> -		return 0;
> +		return -1;

hum, missed this one in previous version.. why did not we fail before?

jirka

Re: [PATCH v3 2/2] perf tool: Fix ppid for synthesized fork events

[Jiri Olsa]

On Tue, Mar 31, 2015 at 04:10:26PM +0200, Jiri Olsa wrote:
> On Mon, Mar 30, 2015 at 02:35:58PM -0600, David Ahern wrote:
> > 363b785f38 added synthesized fork events and set a thread's parent id
> > to itself. Since we are already processing /proc/<pid>/status the ppid
> > can be determined properly. Make it so.
> > 
> > Signed-off-by: David Ahern <dsahern@gmail.com>
> > Cc: Don Zickus <dzickus@redhat.com>
> > Cc: Joe Mario <jmario@redhat.com>
> > Cc: Jiri Olsa <jolsa@redhat.com>
> > ---
> > v3
> > - removed isspace and newline checks; added brackets per Arnaldo's comments
> > 
> > v2:
> > - removed changes to function signature for perf_event__synthesize_comm as
> >   noted by Jiri
> > 
> >  tools/perf/util/event.c | 83 +++++++++++++++++++++++++++++--------------------
> >  1 file changed, 50 insertions(+), 33 deletions(-)
> > 
> > diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> > index 023dd3548a94..5516236df6ab 100644
> > --- a/tools/perf/util/event.c
> > +++ b/tools/perf/util/event.c
> > @@ -51,29 +51,32 @@ static struct perf_sample synth_sample = {
> >  
> >  /*
> >   * Assumes that the first 4095 bytes of /proc/pid/stat contains
> > - * the comm and tgid.
> > + * the comm, tgid and ppid.
> >   */
> > -static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
> > +static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,
> > +				    pid_t *tgid, pid_t *ppid)
> >  {
> >  	char filename[PATH_MAX];
> >  	char bf[4096];
> >  	int fd;
> >  	size_t size = 0, n;
> > -	pid_t tgid = -1;
> > -	char *nl, *name, *tgids;
> > +	char *nl, *name, *tgids, *ppids;
> > +
> > +	*tgid = -1;
> > +	*ppid = -1;
> >  
> >  	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
> >  
> >  	fd = open(filename, O_RDONLY);
> >  	if (fd < 0) {
> >  		pr_debug("couldn't open %s\n", filename);
> > -		return 0;
> > +		return -1;
> 
> hum, missed this one in previous version.. why did not we fail before?

sigh, it was the tgid before, now it's err..  ;-) ook

jirka

Re: [PATCH v3 2/2] perf tool: Fix ppid for synthesized fork events

[Jiri Olsa]

On Mon, Mar 30, 2015 at 02:35:58PM -0600, David Ahern wrote:
> 363b785f38 added synthesized fork events and set a thread's parent id
> to itself. Since we are already processing /proc/<pid>/status the ppid
> can be determined properly. Make it so.
> 
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Cc: Don Zickus <dzickus@redhat.com>
> Cc: Joe Mario <jmario@redhat.com>
> Cc: Jiri Olsa <jolsa@redhat.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

Re: [PATCH v3 2/2] perf tool: Fix ppid for synthesized fork events

[Don Zickus]

On Mon, Mar 30, 2015 at 02:35:58PM -0600, David Ahern wrote:
> 363b785f38 added synthesized fork events and set a thread's parent id
> to itself. Since we are already processing /proc/<pid>/status the ppid
> can be determined properly. Make it so.

Acked-by: Don Zickus <dzickus@redhat.com>

> 
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Cc: Don Zickus <dzickus@redhat.com>
> Cc: Joe Mario <jmario@redhat.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> ---
> v3
> - removed isspace and newline checks; added brackets per Arnaldo's comments
> 
> v2:
> - removed changes to function signature for perf_event__synthesize_comm as
>   noted by Jiri
> 
>  tools/perf/util/event.c | 83 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 50 insertions(+), 33 deletions(-)
> 
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 023dd3548a94..5516236df6ab 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -51,29 +51,32 @@ static struct perf_sample synth_sample = {
>  
>  /*
>   * Assumes that the first 4095 bytes of /proc/pid/stat contains
> - * the comm and tgid.
> + * the comm, tgid and ppid.
>   */
> -static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
> +static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,
> +				    pid_t *tgid, pid_t *ppid)
>  {
>  	char filename[PATH_MAX];
>  	char bf[4096];
>  	int fd;
>  	size_t size = 0, n;
> -	pid_t tgid = -1;
> -	char *nl, *name, *tgids;
> +	char *nl, *name, *tgids, *ppids;
> +
> +	*tgid = -1;
> +	*ppid = -1;
>  
>  	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
>  
>  	fd = open(filename, O_RDONLY);
>  	if (fd < 0) {
>  		pr_debug("couldn't open %s\n", filename);
> -		return 0;
> +		return -1;
>  	}
>  
>  	n = read(fd, bf, sizeof(bf) - 1);
>  	close(fd);
>  	if (n <= 0) {
> -		pr_warning("Couldn't get COMM and tgid for pid %d\n",
> +		pr_warning("Couldn't get COMM, tigd and ppid for pid %d\n",
>  			   pid);
>  		return -1;
>  	}
> @@ -81,6 +84,7 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
>  
>  	name = strstr(bf, "Name:");
>  	tgids = strstr(bf, "Tgid:");
> +	ppids = strstr(bf, "PPid:");
>  
>  	if (name) {
>  		name += 5;  /* strlen("Name:") */
> @@ -103,32 +107,45 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
>  
>  	if (tgids) {
>  		tgids += 5;  /* strlen("Tgid:") */
> -		tgid = atoi(tgids);
> +		*tgid = atoi(tgids);
>  	} else {
>  		pr_debug("Tgid: string not found for pid %d\n", pid);
>  	}
>  
> -	return tgid;
> +	if (ppids) {
> +		ppids += 5;  /* strlen("PPid:") */
> +		*ppid = atoi(ppids);
> +	} else {
> +		pr_debug("PPid: string not found for pid %d\n", pid);
> +	}
> +
> +	return 0;
>  }
>  
> -static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
> -					 struct machine *machine)
> +static int perf_event__prepare_comm(union perf_event *event, pid_t pid,
> +				    struct machine *machine,
> +				    pid_t *tgid, pid_t *ppid)
>  {
>  	size_t size;
> -	pid_t tgid;
> +
> +	*ppid = -1;
>  
>  	memset(&event->comm, 0, sizeof(event->comm));
>  
> -	if (machine__is_host(machine))
> -		tgid = perf_event__get_comm_tgid(pid, event->comm.comm,
> -						 sizeof(event->comm.comm));
> -	else
> -		tgid = machine->pid;
> +	if (machine__is_host(machine)) {
> +		if (perf_event__get_comm_ids(pid, event->comm.comm,
> +					     sizeof(event->comm.comm),
> +					     tgid, ppid) != 0) {
> +			return -1;
> +		}
> +	} else {
> +		*tgid = machine->pid;
> +	}
>  
> -	if (tgid < 0)
> -		goto out;
> +	if (*tgid < 0)
> +		return -1;
>  
> -	event->comm.pid = tgid;
> +	event->comm.pid = *tgid;
>  	event->comm.header.type = PERF_RECORD_COMM;
>  
>  	size = strlen(event->comm.comm) + 1;
> @@ -138,8 +155,8 @@ static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
>  				(sizeof(event->comm.comm) - size) +
>  				machine->id_hdr_size);
>  	event->comm.tid = pid;
> -out:
> -	return tgid;
> +
> +	return 0;
>  }
>  
>  static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
> @@ -147,27 +164,27 @@ static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
>  					 perf_event__handler_t process,
>  					 struct machine *machine)
>  {
> -	pid_t tgid = perf_event__prepare_comm(event, pid, machine);
> +	pid_t tgid, ppid;
>  
> -	if (tgid == -1)
> -		goto out;
> +	if (perf_event__prepare_comm(event, pid, machine, &tgid, &ppid) != 0)
> +		return -1;
>  
>  	if (process(tool, event, &synth_sample, machine) != 0)
>  		return -1;
>  
> -out:
>  	return tgid;
>  }
>  
>  static int perf_event__synthesize_fork(struct perf_tool *tool,
> -				       union perf_event *event, pid_t pid,
> -				       pid_t tgid, perf_event__handler_t process,
> +				       union perf_event *event,
> +				       pid_t pid, pid_t tgid, pid_t ppid,
> +				       perf_event__handler_t process,
>  				       struct machine *machine)
>  {
>  	memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);
>  
> -	event->fork.ppid = tgid;
> -	event->fork.ptid = tgid;
> +	event->fork.ppid = ppid;
> +	event->fork.ptid = ppid;
>  	event->fork.pid  = tgid;
>  	event->fork.tid  = pid;
>  	event->fork.header.type = PERF_RECORD_FORK;
> @@ -359,7 +376,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
>  	char filename[PATH_MAX];
>  	DIR *tasks;
>  	struct dirent dirent, *next;
> -	pid_t tgid;
> +	pid_t tgid, ppid;
>  
>  	/* special case: only send one comm event using passed in pid */
>  	if (!full) {
> @@ -394,12 +411,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
>  		if (*end)
>  			continue;
>  
> -		tgid = perf_event__prepare_comm(comm_event, _pid, machine);
> -		if (tgid == -1)
> +		if (perf_event__prepare_comm(comm_event, _pid, machine,
> +					     &tgid, &ppid) != 0)
>  			return -1;
>  
>  		if (perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
> -						process, machine) < 0)
> +						ppid, process, machine) < 0)
>  			return -1;
>  		/*
>  		 * Send the prepared comm event
> -- 
> 2.2.1
> 

[tip:perf/core] perf tools: Fix ppid for synthesized fork events

[tip-bot for David Ahern]

Commit-ID:  ca6c41c59b964d362823e80442e9e32c31106b29
Gitweb:     http://git.kernel.org/tip/ca6c41c59b964d362823e80442e9e32c31106b29
Author:     David Ahern <dsahern@gmail.com>
AuthorDate: Mon, 30 Mar 2015 14:35:58 -0600
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 31 Mar 2015 17:52:30 -0300

perf tools: Fix ppid for synthesized fork events

363b785f38 added synthesized fork events and set a thread's parent id to
itself. Since we are already processing /proc/<pid>/status the ppid can
be determined properly. Make it so.

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Mario <jmario@redhat.com>
Link: http://lkml.kernel.org/r/1427747758-18510-2-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/event.c | 83 +++++++++++++++++++++++++++++--------------------
 1 file changed, 50 insertions(+), 33 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 023dd35..5516236 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -51,29 +51,32 @@ static struct perf_sample synth_sample = {
 
 /*
  * Assumes that the first 4095 bytes of /proc/pid/stat contains
- * the comm and tgid.
+ * the comm, tgid and ppid.
  */
-static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
+static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,
+				    pid_t *tgid, pid_t *ppid)
 {
 	char filename[PATH_MAX];
 	char bf[4096];
 	int fd;
 	size_t size = 0, n;
-	pid_t tgid = -1;
-	char *nl, *name, *tgids;
+	char *nl, *name, *tgids, *ppids;
+
+	*tgid = -1;
+	*ppid = -1;
 
 	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
 
 	fd = open(filename, O_RDONLY);
 	if (fd < 0) {
 		pr_debug("couldn't open %s\n", filename);
-		return 0;
+		return -1;
 	}
 
 	n = read(fd, bf, sizeof(bf) - 1);
 	close(fd);
 	if (n <= 0) {
-		pr_warning("Couldn't get COMM and tgid for pid %d\n",
+		pr_warning("Couldn't get COMM, tigd and ppid for pid %d\n",
 			   pid);
 		return -1;
 	}
@@ -81,6 +84,7 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 
 	name = strstr(bf, "Name:");
 	tgids = strstr(bf, "Tgid:");
+	ppids = strstr(bf, "PPid:");
 
 	if (name) {
 		name += 5;  /* strlen("Name:") */
@@ -103,32 +107,45 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 
 	if (tgids) {
 		tgids += 5;  /* strlen("Tgid:") */
-		tgid = atoi(tgids);
+		*tgid = atoi(tgids);
 	} else {
 		pr_debug("Tgid: string not found for pid %d\n", pid);
 	}
 
-	return tgid;
+	if (ppids) {
+		ppids += 5;  /* strlen("PPid:") */
+		*ppid = atoi(ppids);
+	} else {
+		pr_debug("PPid: string not found for pid %d\n", pid);
+	}
+
+	return 0;
 }
 
-static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
-					 struct machine *machine)
+static int perf_event__prepare_comm(union perf_event *event, pid_t pid,
+				    struct machine *machine,
+				    pid_t *tgid, pid_t *ppid)
 {
 	size_t size;
-	pid_t tgid;
+
+	*ppid = -1;
 
 	memset(&event->comm, 0, sizeof(event->comm));
 
-	if (machine__is_host(machine))
-		tgid = perf_event__get_comm_tgid(pid, event->comm.comm,
-						 sizeof(event->comm.comm));
-	else
-		tgid = machine->pid;
+	if (machine__is_host(machine)) {
+		if (perf_event__get_comm_ids(pid, event->comm.comm,
+					     sizeof(event->comm.comm),
+					     tgid, ppid) != 0) {
+			return -1;
+		}
+	} else {
+		*tgid = machine->pid;
+	}
 
-	if (tgid < 0)
-		goto out;
+	if (*tgid < 0)
+		return -1;
 
-	event->comm.pid = tgid;
+	event->comm.pid = *tgid;
 	event->comm.header.type = PERF_RECORD_COMM;
 
 	size = strlen(event->comm.comm) + 1;
@@ -138,8 +155,8 @@ static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
 				(sizeof(event->comm.comm) - size) +
 				machine->id_hdr_size);
 	event->comm.tid = pid;
-out:
-	return tgid;
+
+	return 0;
 }
 
 static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
@@ -147,27 +164,27 @@ static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
 					 perf_event__handler_t process,
 					 struct machine *machine)
 {
-	pid_t tgid = perf_event__prepare_comm(event, pid, machine);
+	pid_t tgid, ppid;
 
-	if (tgid == -1)
-		goto out;
+	if (perf_event__prepare_comm(event, pid, machine, &tgid, &ppid) != 0)
+		return -1;
 
 	if (process(tool, event, &synth_sample, machine) != 0)
 		return -1;
 
-out:
 	return tgid;
 }
 
 static int perf_event__synthesize_fork(struct perf_tool *tool,
-				       union perf_event *event, pid_t pid,
-				       pid_t tgid, perf_event__handler_t process,
+				       union perf_event *event,
+				       pid_t pid, pid_t tgid, pid_t ppid,
+				       perf_event__handler_t process,
 				       struct machine *machine)
 {
 	memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);
 
-	event->fork.ppid = tgid;
-	event->fork.ptid = tgid;
+	event->fork.ppid = ppid;
+	event->fork.ptid = ppid;
 	event->fork.pid  = tgid;
 	event->fork.tid  = pid;
 	event->fork.header.type = PERF_RECORD_FORK;
@@ -359,7 +376,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
 	char filename[PATH_MAX];
 	DIR *tasks;
 	struct dirent dirent, *next;
-	pid_t tgid;
+	pid_t tgid, ppid;
 
 	/* special case: only send one comm event using passed in pid */
 	if (!full) {
@@ -394,12 +411,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
 		if (*end)
 			continue;
 
-		tgid = perf_event__prepare_comm(comm_event, _pid, machine);
-		if (tgid == -1)
+		if (perf_event__prepare_comm(comm_event, _pid, machine,
+					     &tgid, &ppid) != 0)
 			return -1;
 
 		if (perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
-						process, machine) < 0)
+						ppid, process, machine) < 0)
 			return -1;
 		/*
 		 * Send the prepared comm event

Re: [PATCH v2 1/2] perf tool: Refactor comm/tgid lookup

[Jiri Olsa]

On Mon, Mar 30, 2015 at 02:35:57PM -0600, David Ahern wrote:
> Rather than parsing /proc/pid/status file one line at a time, read
> it into a buffer in one shot and search for all strings in one pass.
> 
> tgid conversion also simplified -- removing the isspace walk. As
> noted by Arnaldo those are not needed for atoi == strtol calls.
> 
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Cc: Don Zickus <dzickus@redhat.com>
> Cc: Joe Mario <jmario@redhat.com>
> Cc: Jiri Olsa <jolsa@redhat.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

Re: [PATCH v2 1/2] perf tool: Refactor comm/tgid lookup

[Arnaldo Carvalho de Melo]

Em Tue, Mar 31, 2015 at 04:35:46PM +0200, Jiri Olsa escreveu:
> On Mon, Mar 30, 2015 at 02:35:57PM -0600, David Ahern wrote:
> > Rather than parsing /proc/pid/status file one line at a time, read
> > it into a buffer in one shot and search for all strings in one pass.
> > 
> > tgid conversion also simplified -- removing the isspace walk. As
> > noted by Arnaldo those are not needed for atoi == strtol calls.
> > 
> > Signed-off-by: David Ahern <dsahern@gmail.com>
> > Cc: Don Zickus <dzickus@redhat.com>
> > Cc: Joe Mario <jmario@redhat.com>
> > Cc: Jiri Olsa <jolsa@redhat.com>
> 
> Acked-by: Jiri Olsa <jolsa@kernel.org>

Thanks, applied both, with Jiri's acks.

- Arnaldo

Re: [PATCH v2 1/2] perf tool: Refactor comm/tgid lookup

[Don Zickus]

On Mon, Mar 30, 2015 at 02:35:57PM -0600, David Ahern wrote:
> Rather than parsing /proc/pid/status file one line at a time, read
> it into a buffer in one shot and search for all strings in one pass.
> 
> tgid conversion also simplified -- removing the isspace walk. As
> noted by Arnaldo those are not needed for atoi == strtol calls.

Seeing Jiri is happy now. :-) 

Acked-by: Don Zickus <dzickus@redhat.com>

> 
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Cc: Don Zickus <dzickus@redhat.com>
> Cc: Joe Mario <jmario@redhat.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> ---
> v2:
> - removed the isspace checks on tgid string
> 
>  tools/perf/util/event.c | 72 ++++++++++++++++++++++++++++++-------------------
>  1 file changed, 44 insertions(+), 28 deletions(-)
> 
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index d5efa5092ce6..023dd3548a94 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -49,48 +49,64 @@ static struct perf_sample synth_sample = {
>  	.period	   = 1,
>  };
>  
> +/*
> + * Assumes that the first 4095 bytes of /proc/pid/stat contains
> + * the comm and tgid.
> + */
>  static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
>  {
>  	char filename[PATH_MAX];
> -	char bf[BUFSIZ];
> -	FILE *fp;
> -	size_t size = 0;
> +	char bf[4096];
> +	int fd;
> +	size_t size = 0, n;
>  	pid_t tgid = -1;
> +	char *nl, *name, *tgids;
>  
>  	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
>  
> -	fp = fopen(filename, "r");
> -	if (fp == NULL) {
> +	fd = open(filename, O_RDONLY);
> +	if (fd < 0) {
>  		pr_debug("couldn't open %s\n", filename);
>  		return 0;
>  	}
>  
> -	while (!comm[0] || (tgid < 0)) {
> -		if (fgets(bf, sizeof(bf), fp) == NULL) {
> -			pr_warning("couldn't get COMM and pgid, malformed %s\n",
> -				   filename);
> -			break;
> -		}
> +	n = read(fd, bf, sizeof(bf) - 1);
> +	close(fd);
> +	if (n <= 0) {
> +		pr_warning("Couldn't get COMM and tgid for pid %d\n",
> +			   pid);
> +		return -1;
> +	}
> +	bf[n] = '\0';
>  
> -		if (memcmp(bf, "Name:", 5) == 0) {
> -			char *name = bf + 5;
> -			while (*name && isspace(*name))
> -				++name;
> -			size = strlen(name) - 1;
> -			if (size >= len)
> -				size = len - 1;
> -			memcpy(comm, name, size);
> -			comm[size] = '\0';
> -
> -		} else if (memcmp(bf, "Tgid:", 5) == 0) {
> -			char *tgids = bf + 5;
> -			while (*tgids && isspace(*tgids))
> -				++tgids;
> -			tgid = atoi(tgids);
> -		}
> +	name = strstr(bf, "Name:");
> +	tgids = strstr(bf, "Tgid:");
> +
> +	if (name) {
> +		name += 5;  /* strlen("Name:") */
> +
> +		while (*name && isspace(*name))
> +			++name;
> +
> +		nl = strchr(name, '\n');
> +		if (nl)
> +			*nl = '\0';
> +
> +		size = strlen(name);
> +		if (size >= len)
> +			size = len - 1;
> +		memcpy(comm, name, size);
> +		comm[size] = '\0';
> +	} else {
> +		pr_debug("Name: string not found for pid %d\n", pid);
>  	}
>  
> -	fclose(fp);
> +	if (tgids) {
> +		tgids += 5;  /* strlen("Tgid:") */
> +		tgid = atoi(tgids);
> +	} else {
> +		pr_debug("Tgid: string not found for pid %d\n", pid);
> +	}
>  
>  	return tgid;
>  }
> -- 
> 2.2.1
> 

[tip:perf/core] perf tools: Refactor comm/tgid lookup

[tip-bot for David Ahern]

Commit-ID:  5aa0b030e8d29d6719c144818814b519cfcb105c
Gitweb:     http://git.kernel.org/tip/5aa0b030e8d29d6719c144818814b519cfcb105c
Author:     David Ahern <dsahern@gmail.com>
AuthorDate: Mon, 30 Mar 2015 14:35:57 -0600
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 31 Mar 2015 17:52:30 -0300

perf tools: Refactor comm/tgid lookup

Rather than parsing /proc/pid/status file one line at a time, read it
into a buffer in one shot and search for all strings in one pass.

tgid conversion also simplified -- removing the isspace walk. As noted
by Arnaldo those are not needed for atoi == strtol calls.

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Mario <jmario@redhat.com>
Link: http://lkml.kernel.org/r/1427747758-18510-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/event.c | 72 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 44 insertions(+), 28 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index d5efa50..023dd35 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -49,48 +49,64 @@ static struct perf_sample synth_sample = {
 	.period	   = 1,
 };
 
+/*
+ * Assumes that the first 4095 bytes of /proc/pid/stat contains
+ * the comm and tgid.
+ */
 static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 {
 	char filename[PATH_MAX];
-	char bf[BUFSIZ];
-	FILE *fp;
-	size_t size = 0;
+	char bf[4096];
+	int fd;
+	size_t size = 0, n;
 	pid_t tgid = -1;
+	char *nl, *name, *tgids;
 
 	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
 
-	fp = fopen(filename, "r");
-	if (fp == NULL) {
+	fd = open(filename, O_RDONLY);
+	if (fd < 0) {
 		pr_debug("couldn't open %s\n", filename);
 		return 0;
 	}
 
-	while (!comm[0] || (tgid < 0)) {
-		if (fgets(bf, sizeof(bf), fp) == NULL) {
-			pr_warning("couldn't get COMM and pgid, malformed %s\n",
-				   filename);
-			break;
-		}
+	n = read(fd, bf, sizeof(bf) - 1);
+	close(fd);
+	if (n <= 0) {
+		pr_warning("Couldn't get COMM and tgid for pid %d\n",
+			   pid);
+		return -1;
+	}
+	bf[n] = '\0';
 
-		if (memcmp(bf, "Name:", 5) == 0) {
-			char *name = bf + 5;
-			while (*name && isspace(*name))
-				++name;
-			size = strlen(name) - 1;
-			if (size >= len)
-				size = len - 1;
-			memcpy(comm, name, size);
-			comm[size] = '\0';
-
-		} else if (memcmp(bf, "Tgid:", 5) == 0) {
-			char *tgids = bf + 5;
-			while (*tgids && isspace(*tgids))
-				++tgids;
-			tgid = atoi(tgids);
-		}
+	name = strstr(bf, "Name:");
+	tgids = strstr(bf, "Tgid:");
+
+	if (name) {
+		name += 5;  /* strlen("Name:") */
+
+		while (*name && isspace(*name))
+			++name;
+
+		nl = strchr(name, '\n');
+		if (nl)
+			*nl = '\0';
+
+		size = strlen(name);
+		if (size >= len)
+			size = len - 1;
+		memcpy(comm, name, size);
+		comm[size] = '\0';
+	} else {
+		pr_debug("Name: string not found for pid %d\n", pid);
 	}
 
-	fclose(fp);
+	if (tgids) {
+		tgids += 5;  /* strlen("Tgid:") */
+		tgid = atoi(tgids);
+	} else {
+		pr_debug("Tgid: string not found for pid %d\n", pid);
+	}
 
 	return tgid;
 }