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Message-Id: <1427302270-10178-1-git-send-email-dsahern@gmail.com>
Date: Wed, 25 Mar 2015 10:51:10 -0600
From: David Ahern <dsahern@...il.com>
To: acme@...nel.org
Cc: linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
Don Zickus <dzickus@...hat.com>, Joe Mario <jmario@...hat.com>,
Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH v2] perf tool: 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.
Performance impact measured on a sparc based T5-8 (1024 CPUs):
$ ps -efL | wc -l
20185
Current code:
$ time perf record -o perf-no-ppid.data -e cpu-clock -F 1000 -a -v -BN -- usleep 1
mmap size 532480B
[ perf record: Woken up 0 times to write data ]
failed to write feature 9
[ perf record: Captured and wrote 0.000 MB perf-no-ppid.data ]
real 0m26.144s
user 0m0.452s
sys 0m25.564s
With PPID patch:
$ time ./perf_ppid record -o perf-ppid.data -e cpu-clock -F 1000 -a -v -BN -- usleep 1
mmap size 532480B
[ perf record: Woken up 0 times to write data ]
failed to write feature 9
[ perf record: Captured and wrote 0.000 MB perf-ppid.data ]
real 0m25.743s
user 0m0.268s
sys 0m25.368s
Signed-off-by: David Ahern <dsahern@...il.com>
Cc: Don Zickus <dzickus@...hat.com>
Cc: Joe Mario <jmario@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
---
v2:
- removed loop in place of 1 read and processing a buffer
tools/perf/util/event.c | 178 ++++++++++++++++++++++++++++++------------------
1 file changed, 110 insertions(+), 68 deletions(-)
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index d5efa5092ce6..e98cbba56033 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -49,70 +49,115 @@ static struct perf_sample synth_sample = {
.period = 1,
};
-static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
+/*
+ * Assumes that the first 4095 bytes of /proc/pid/stat contains
+ * the comm, tgid and ppid.
+ */
+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[BUFSIZ];
- FILE *fp;
- size_t size = 0;
- pid_t tgid = -1;
+ char bf[4096];
+ int fd;
+ size_t size = 0, n;
+ char *nl, *name, *tgids, *ppids;
+
+ *tgid = -1;
+ *ppid = -1;
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;
+ return -1;
}
- 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;
- }
-
- 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);
- }
+ n = read(fd, bf, sizeof(bf) - 1);
+ close(fd);
+ if (n <= 0) {
+ pr_warning("Couldn't get COMM, tigd and ppid for pid %d\n",
+ pid);
+ return -1;
}
+ bf[n] = '\0';
- fclose(fp);
+ name = strstr(bf, "Name:");
+ tgids = strstr(bf, "Tgid:");
+ ppids = strstr(bf, "PPid:");
+
+ 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);
+
+ if (tgids) {
+ tgids += 5; /* strlen("Tgid:") */
+ while (*tgids && isspace(*tgids))
+ ++tgids;
+
+ nl = strchr(tgids, '\n');
+ if (nl)
+ *nl = '\0';
+
+ *tgid = atoi(tgids);
+
+ } else
+ pr_debug("Tgid: string not found for pid %d\n", pid);
+
+ if (ppids) {
+ ppids += 5; /* strlen("PPid:") */
+
+ while (*ppids && isspace(*ppids))
+ ++ppids;
+
+ nl = strchr(ppids, '\n');
+ if (nl)
+ *nl = '\0';
+
+ *ppid = atoi(ppids);
+ } else
+ pr_debug("PPid: string not found for pid %d\n", pid);
- return tgid;
+ 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;
@@ -122,36 +167,35 @@ 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,
- union perf_event *event, pid_t pid,
- perf_event__handler_t process,
- struct machine *machine)
+static int perf_event__synthesize_comm(struct perf_tool *tool,
+ union perf_event *event, pid_t pid,
+ perf_event__handler_t process,
+ struct machine *machine,
+ pid_t *tgid, pid_t *ppid)
{
- pid_t tgid = perf_event__prepare_comm(event, pid, machine);
-
- 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;
+ return 0;
}
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;
@@ -343,14 +387,12 @@ 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) {
- tgid = perf_event__synthesize_comm(tool, comm_event, pid,
- process, machine);
-
- if (tgid == -1)
+ if (perf_event__synthesize_comm(tool, comm_event, pid,
+ process, machine, &tgid, &ppid) != 0)
return -1;
return perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
@@ -378,12 +420,12 @@ 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
--
2.1.0
--
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