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Commit 5aa0b030 authored by David Ahern's avatar David Ahern Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarDavid Ahern <dsahern@gmail.com>
Acked-by: default avatarDon Zickus <dzickus@redhat.com>
Acked-by: default avatarJiri 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 73dbcd65

tools/perf/util/event.c

+44 −28
Original line number Diff line number Diff line
@@ -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';



	name = strstr(bf, "Name:");

	tgids = strstr(bf, "Tgid:");



	if (name) {

		name += 5;  /* strlen("Name:") */



		if (memcmp(bf, "Name:", 5) == 0) {

			char *name = bf + 5;

		while (*name && isspace(*name))

			++name;

			size = strlen(name) - 1;



		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);

	}



		} else if (memcmp(bf, "Tgid:", 5) == 0) {

			char *tgids = bf + 5;

			while (*tgids && isspace(*tgids))

				++tgids;

	if (tgids) {

		tgids += 5;  /* strlen("Tgid:") */

		tgid = atoi(tgids);

	} else {

		pr_debug("Tgid: string not found for pid %d\n", pid);

	}

	}



	fclose(fp);



	return tgid;

}