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 8CDA5C2D0EC for ; Fri, 10 Apr 2020 03:41:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 53CD2206DD for ; Fri, 10 Apr 2020 03:41:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JEA+DW/s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726703AbgDJDk6 (ORCPT ); Thu, 9 Apr 2020 23:40:58 -0400 Received: from mail-pf1-f201.google.com ([209.85.210.201]:48316 "EHLO mail-pf1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726679AbgDJDk6 (ORCPT ); Thu, 9 Apr 2020 23:40:58 -0400 Received: by mail-pf1-f201.google.com with SMTP id d16so736612pfo.15 for ; Thu, 09 Apr 2020 20:40:56 -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=9pwCl3ybqOSgMds6/j+ZEn9sFNNLR0w3RAqz91zqrV0=; b=JEA+DW/suf/S7ZT5OvZmRj4vsUfS9W0sip+NrENSVmeJDM1Y6fytkJQOZfaZx9rg/U avMPnLF2DHhoHZx49EvZgnCGYitqbZDFHeTaCtjHNeapR7U16d3KOJofvqoJAGfgLjRa PkkFicNyLbbaxcKSsQcJ7uucZL6JuWLk6ofohmYR8B4aN/vlF9QLFkgwfnKYJy0C/LMJ lESz7pTzC1FFV2/XTrkQrjuU9fMkw8S6R3q4nmdLS/Qw+FxXLCq4OcZv09VyRtaaP8st 289gCldko3jKkOsJRG6q8DDWQMUnrG0hRroIzNzbbwW4E89Rr/ngdQ7XO3xBeUte00ai se1w== 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=9pwCl3ybqOSgMds6/j+ZEn9sFNNLR0w3RAqz91zqrV0=; b=JyQuG1OVskbtf+LROIDehiHvnOo8BweWtA3xBF0HCF62KEe9LDnGmuGjpfzA6dOptW qZEYgQdq13BoLqBqe38U2GnqBguuHuab0LuCmPZ4iq1oWvkaZD71CSsXrCSbDjmUnBAL yeY422YSyxR6Gy0fCzwEMxPrHS8NqhvCvf5EpTHPVgb/XHwgOuJskeK6AMnLYL32QCz2 hkdHRajccQo0APL0tM1rNIRZY8n9eDbDZtSkyvmYGHIgPdUAY854qd7EXGAzHc0Irnwu ePUJrMwIiOQPMWqgjmqosN/NFIJ9uMAxTsY3vYiUxZrZAvB2PczUyo58N7O8/FqA/btu Q1yA== X-Gm-Message-State: AGi0PuYfNW333/WYq6BaT/dbA4zhcR6KvxtC8cjtnDLv/j5QRmee0S2L cBuCzkecPQbHvGLNK7vf8gMhyV/2jSvb X-Google-Smtp-Source: APiQypIeBl/IBntQTYFsqbsrozDfepjaFN5jb7BKSocGmuas7rdv9TcOQo+gusVQfp+N6qfPa6HWNuUo5QB5 X-Received: by 2002:a63:1910:: with SMTP id z16mr2581685pgl.156.1586490055549; Thu, 09 Apr 2020 20:40:55 -0700 (PDT) Date: Thu, 9 Apr 2020 20:40:48 -0700 In-Reply-To: <20200410034048.144150-1-irogers@google.com> Message-Id: <20200410034048.144150-2-irogers@google.com> Mime-Version: 1.0 References: <20200410034048.144150-1-irogers@google.com> X-Mailer: git-send-email 2.26.0.110.g2183baf09c-goog Subject: [PATCH v3 2/2] 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 9d4aa951eaa6..1ea9adaef9c7 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -37,6 +37,7 @@ #include #include /* To get things like MAP_HUGETLB even on older libc headers */ #include +#include #include #include #include @@ -273,6 +274,79 @@ 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, @@ -280,9 +354,9 @@ 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; @@ -295,28 +369,39 @@ 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. " @@ -327,23 +412,6 @@ 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; /* @@ -354,23 +422,8 @@ 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; @@ -380,17 +433,17 @@ 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) - @@ -409,7 +462,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, break; } - fclose(fp); + close(io.fd); return rc; } -- 2.26.0.110.g2183baf09c-goog