From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C12A9C43331 for ; Thu, 2 Apr 2020 15:44:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8205F2063A for ; Thu, 2 Apr 2020 15:44:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="A1ASF1c0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389513AbgDBPoS (ORCPT ); Thu, 2 Apr 2020 11:44:18 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:57112 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389491AbgDBPoP (ORCPT ); Thu, 2 Apr 2020 11:44:15 -0400 Received: by mail-qk1-f201.google.com with SMTP id o14so3362901qke.23 for ; Thu, 02 Apr 2020 08:44:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=8NafyOVUhJE7GQyMOzfSsmcL2IBU8ziCZAboaynAxpM=; b=A1ASF1c0OjaklxAKqlD5pR7jJ9OHJEjVvKp5yNUpXDaJugIqw2vzGJOiB2025SyEK8 6o3QHEquIz9/dTOuBtaMbM9ndh+JGm+R5q/ZuUgNihNVM2Rzc/n0nMdzyrB4IubZnwq2 jQTwLWn0H+dr9e3KmX/zoEr/NMAeVhe7/FeXA27vuwQ2u1oHabB0FRn1Pi6YOuABvIgi q6pVjw5MrRQMrt2WzXOsEqS0dvUAi2JQ+qeFNXpOBwOl9Z/XMPY7LManFLlz48E0zCfk D2VdxJdX52TYK+Q3p5rVC5IuOeWX4tB9uhNtqJee/ERFCItBH3pFrJ6N95I72gmg4/g8 P65g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=8NafyOVUhJE7GQyMOzfSsmcL2IBU8ziCZAboaynAxpM=; b=TbCn9C4RFTw91zKWLgMR8fzle8IxJev/KPA87y1er5s2M8WzQerrCExjNO4bOJdDrh O2/SRrx41IgrCaUhgqjWh69Kc/7BeH3SQJTEEuQXxmWVzMyR8AIOzDrpT1C0ObIg8x+P 5qQ2DAd3fAVeRCyyHuXse4XLXK8TuRtkSECmiODRo60b1Tg0HX2Etsd/dTZ9ndIZPP9G Ktd5FpVSiLTYkCDky5mK2KHds+zfvWt1vSFVaxNoeLPTyb3Py56cfsOSfTpKlPRKjTQA AScmnuDK9BI0su/cTGU4xCRmLy8NZJIixrmibO9QZZ/XLxh6U7ZbPatTXyOvfw7TRJji kgzw== X-Gm-Message-State: AGi0PubFY1U8kaEz1ljbhJPa3gAyR/ICQRW4qpfVaBRj7rtC+SIu2iko ulKCakzAnyDx1wZjj8Sy+LPQTj4BjuES X-Google-Smtp-Source: APiQypJ1r+Ovywn2qmjdTUpD15l2BGwgt/Qq22GeA1PQtD6rirgwP0lRcDkC7WOwWW0RzuKAh3IZ6nQBL1sT X-Received: by 2002:a0c:fe04:: with SMTP id x4mr3866703qvr.69.1585842254585; Thu, 02 Apr 2020 08:44:14 -0700 (PDT) Date: Thu, 2 Apr 2020 08:43:57 -0700 In-Reply-To: <20200402154357.107873-1-irogers@google.com> Message-Id: <20200402154357.107873-6-irogers@google.com> Mime-Version: 1.0 References: <20200402154357.107873-1-irogers@google.com> X-Mailer: git-send-email 2.26.0.rc2.310.g2932bb562d-goog Subject: [PATCH v2 5/5] perf synthetic events: Remove use of sscanf from /proc reading From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Petr Mladek , Andrey Zhizhikin , Kefeng Wang , Thomas Gleixner , Kan Liang , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: Stephane Eranian , Ian Rogers Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The synthesize benchmark, run on a single process and thread, shows perf_event__synthesize_mmap_events as the hottest function with fgets and sscanf taking the majority of execution time. fscanf performs similarly well. Replace the scanf call with manual reading of each field of the /proc/pid/maps line, and remove some unnecessary buffering. This change also addresses potential, but unlikely, buffer overruns for the string values read by scanf. Performance before is: Average synthesis took: 120.195100 usec Average data synthesis took: 156.582300 usec And after is: Average synthesis took: 67.189100 usec Average data synthesis took: 102.451600 usec On a Intel Xeon 6154 compiling with Debian gcc 9.2.1. Signed-off-by: Ian Rogers --- tools/perf/util/synthetic-events.c | 157 +++++++++++++++++++---------- 1 file changed, 105 insertions(+), 52 deletions(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 1f3d8d4bb879..ebe48e35499d 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -36,6 +36,7 @@ #include #include /* To get things like MAP_HUGETLB even on older libc headers */ #include +#include #include #include #include @@ -272,6 +273,79 @@ static int perf_event__synthesize_fork(struct perf_tool *tool, return 0; } +static bool read_proc_maps_line(struct io *io, __u64 *start, __u64 *end, + u32 *prot, u32 *flags, __u64 *offset, + u32 *maj, u32 *min, + __u64 *inode, + ssize_t pathname_size, char *pathname) +{ + __u64 temp; + int ch; + char *start_pathname = pathname; + + if (io__get_hex(io, start) != '-') + return false; + if (io__get_hex(io, end) != ' ') + return false; + + /* map protection and flags bits */ + *prot = 0; + ch = io__get_char(io); + if (ch == 'r') + *prot |= PROT_READ; + else if (ch != '-') + return false; + ch = io__get_char(io); + if (ch == 'w') + *prot |= PROT_WRITE; + else if (ch != '-') + return false; + ch = io__get_char(io); + if (ch == 'x') + *prot |= PROT_EXEC; + else if (ch != '-') + return false; + ch = io__get_char(io); + if (ch == 's') + *flags = MAP_SHARED; + else if (ch == 'p') + *flags = MAP_PRIVATE; + else + return false; + if (io__get_char(io) != ' ') + return false; + + if (io__get_hex(io, offset) != ' ') + return false; + + if (io__get_hex(io, &temp) != ':') + return false; + *maj = temp; + if (io__get_hex(io, &temp) != ' ') + return false; + *min = temp; + + ch = io__get_dec(io, inode); + if (ch != ' ') { + *pathname = '\0'; + return ch == '\n'; + } + do { + ch = io__get_char(io); + } while (ch == ' '); + while (true) { + if (ch < 0) + return false; + if (ch == '\0' || ch == '\n' || + (pathname + 1 - start_pathname) >= pathname_size) { + *pathname = '\0'; + return true; + } + *pathname++ = ch; + ch = io__get_char(io); + } +} + int perf_event__synthesize_mmap_events(struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, @@ -279,9 +353,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, struct machine *machine, bool mmap_data) { - FILE *fp; unsigned long long t; char bf[BUFSIZ]; + struct io io; bool truncation = false; unsigned long long timeout = proc_map_timeout * 1000000ULL; int rc = 0; @@ -294,28 +368,39 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, snprintf(bf, sizeof(bf), "%s/proc/%d/task/%d/maps", machine->root_dir, pid, pid); - fp = fopen(bf, "r"); - if (fp == NULL) { + io.fd = open(bf, O_RDONLY, 0); + if (io.fd < 0) { /* * We raced with a task exiting - just return: */ pr_debug("couldn't open %s\n", bf); return -1; } + io__init(&io, io.fd, bf, sizeof(bf)); event->header.type = PERF_RECORD_MMAP2; t = rdclock(); - while (1) { - char prot[5]; - char execname[PATH_MAX]; - char anonstr[] = "//anon"; - unsigned int ino; + while (!io.eof) { + static const char anonstr[] = "//anon"; size_t size; - ssize_t n; - if (fgets(bf, sizeof(bf), fp) == NULL) - break; + /* ensure null termination since stack will be reused. */ + event->mmap2.filename[0] = '\0'; + + /* 00400000-0040c000 r-xp 00000000 fd:01 41038 /bin/cat */ + if (!read_proc_maps_line(&io, + &event->mmap2.start, + &event->mmap2.len, + &event->mmap2.prot, + &event->mmap2.flags, + &event->mmap2.pgoff, + &event->mmap2.maj, + &event->mmap2.min, + &event->mmap2.ino, + sizeof(event->mmap2.filename), + event->mmap2.filename)) + continue; if ((rdclock() - t) > timeout) { pr_warning("Reading %s/proc/%d/task/%d/maps time out. " @@ -326,23 +411,6 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, goto out; } - /* ensure null termination since stack will be reused. */ - strcpy(execname, ""); - - /* 00400000-0040c000 r-xp 00000000 fd:01 41038 /bin/cat */ - n = sscanf(bf, "%"PRI_lx64"-%"PRI_lx64" %s %"PRI_lx64" %x:%x %u %[^\n]\n", - &event->mmap2.start, &event->mmap2.len, prot, - &event->mmap2.pgoff, &event->mmap2.maj, - &event->mmap2.min, - &ino, execname); - - /* - * Anon maps don't have the execname. - */ - if (n < 7) - continue; - - event->mmap2.ino = (u64)ino; event->mmap2.ino_generation = 0; /* @@ -353,23 +421,8 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, else event->header.misc = PERF_RECORD_MISC_GUEST_USER; - /* map protection and flags bits */ - event->mmap2.prot = 0; - event->mmap2.flags = 0; - if (prot[0] == 'r') - event->mmap2.prot |= PROT_READ; - if (prot[1] == 'w') - event->mmap2.prot |= PROT_WRITE; - if (prot[2] == 'x') - event->mmap2.prot |= PROT_EXEC; - - if (prot[3] == 's') - event->mmap2.flags |= MAP_SHARED; - else - event->mmap2.flags |= MAP_PRIVATE; - - if (prot[2] != 'x') { - if (!mmap_data || prot[0] != 'r') + if ((event->mmap2.prot & PROT_EXEC) == 0) { + if (!mmap_data || (event->mmap2.prot & PROT_READ) == 0) continue; event->header.misc |= PERF_RECORD_MISC_MMAP_DATA; @@ -379,17 +432,17 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, if (truncation) event->header.misc |= PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT; - if (!strcmp(execname, "")) - strcpy(execname, anonstr); + if (!strcmp(event->mmap2.filename, "")) + strcpy(event->mmap2.filename, anonstr); if (hugetlbfs_mnt_len && - !strncmp(execname, hugetlbfs_mnt, hugetlbfs_mnt_len)) { - strcpy(execname, anonstr); + !strncmp(event->mmap2.filename, hugetlbfs_mnt, + hugetlbfs_mnt_len)) { + strcpy(event->mmap2.filename, anonstr); event->mmap2.flags |= MAP_HUGETLB; } - size = strlen(execname) + 1; - memcpy(event->mmap2.filename, execname, size); + size = strlen(event->mmap2.filename) + 1; size = PERF_ALIGN(size, sizeof(u64)); event->mmap2.len -= event->mmap.start; event->mmap2.header.size = (sizeof(event->mmap2) - @@ -408,7 +461,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, break; } - fclose(fp); + close(io.fd); return rc; } -- 2.26.0.rc2.310.g2932bb562d-goog