On 3/30/15 2:01 AM, Jiri Olsa wrote:
On Sun, Mar 29, 2015 at 04:30:01PM -0600, David Ahern wrote:
SNIP
+ 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;
- }
-
- 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);
we have filename__read_str, which will read whole file into buffer,
and you dont need to worry about the file size.. not that there's
any worry wrt /proc/<pid>/status file, but who knows.. ;-)
hmmm.... I did not know about that function. But I don't think we want
to use it for this case: This function is called a LOT (think 50k or
100k threads) and we want to synthesize the threads as fast as possible.
Using stack (like above) is much faster than dealing with malloc and
free on each pass.
David
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
