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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>
This commit is contained in:
David Ahern 2015-03-30 14:35:57 -06:00 committed by Arnaldo Carvalho de Melo
parent 73dbcd6537
commit 5aa0b030e8
1 changed files with 43 additions and 27 deletions
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70
tools/perf/util/event.c
View File

@ -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';
name = strstr(bf, "Name:");
tgids = strstr(bf, "Tgid:");
} else if (memcmp(bf, "Tgid:", 5) == 0) {
char *tgids = bf + 5;
while (*tgids && isspace(*tgids))
++tgids;
tgid = atoi(tgids);
}
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;
}