From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753487AbbCaU77 (ORCPT ); Tue, 31 Mar 2015 16:59:59 -0400 Received: from mail.kernel.org ([198.145.29.136]:47049 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753377AbbCaU7z (ORCPT ); Tue, 31 Mar 2015 16:59:55 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, David Ahern , Joe Mario , Arnaldo Carvalho de Melo Subject: [PATCH 3/6] perf tools: Refactor comm/tgid lookup Date: Tue, 31 Mar 2015 17:59:40 -0300 Message-Id: <1427835583-29711-4-git-send-email-acme@kernel.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1427835583-29711-1-git-send-email-acme@kernel.org> References: <1427835583-29711-1-git-send-email-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: 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 Acked-by: Don Zickus Acked-by: Jiri Olsa Cc: Joe Mario Link: http://lkml.kernel.org/r/1427747758-18510-1-git-send-email-dsahern@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- 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; } -- 1.9.3