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 5C233C43331 for ; Wed, 1 Apr 2020 23:40:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 181BD2082F for ; Wed, 1 Apr 2020 23:40:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Lwjrj4jR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387568AbgDAXkq (ORCPT ); Wed, 1 Apr 2020 19:40:46 -0400 Received: from mail-pj1-f73.google.com ([209.85.216.73]:39643 "EHLO mail-pj1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387485AbgDAXkk (ORCPT ); Wed, 1 Apr 2020 19:40:40 -0400 Received: by mail-pj1-f73.google.com with SMTP id t17so1639073pjr.4 for ; Wed, 01 Apr 2020 16:40:37 -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=7pHbhugoEMyVUIKjNa3QOHpR63KbMWvyM+5KMBHczmQ=; b=Lwjrj4jR6T5gyFOZ/7SquvRA00VXtdkPOXrT6NumljoqJpNXvYAF83K6X2AzRQEtyh I6IRAG8s/ph1pmUBi+4WE2BM2fyfv+B4L4wh1P0YFR2eiBHj4H2UIDj3NgRAFWSlpmyh GKGuAdLIijm/5M7wMIXQlbQON80W7Jl8RY4uT/VCDIu7kbzVt+7p3sCdjDtjv23yJ1PP uiXSi535hn5dwwXp1J+8yE8vwxiJ5ljlI987jsL61iEpGZTMDPoUtk+OHZXrztASBILK UABWKFsOpG31keBUOQDObrVw2+UOsMv3SKkmfhH99BSMeaecoMN8xax2a1UibLLTx2t+ pbKA== 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=7pHbhugoEMyVUIKjNa3QOHpR63KbMWvyM+5KMBHczmQ=; b=VoJj0GppRS7o1Cx/A+SLwwHKrrbDUlmafrkXqh32tTF2YuR/cda9oiU9zL9ZW1zf/L Cv693vzZDF44ZkUe/Ke+WdOY1OKdHIS04C4rTOZFFqJLGlu3YlCnVEy768G4iyVs4Dk1 t6kvhNvOt2hHFq9UsB9TwTX54Y7D9H3H6jdAtkYt+5zBLc3S7JFJV4YgMvL5WZojaJ1R /1nNk2N9M1MkHE5FuLOE8yyD3df53CeJyoHqL06PMYlUHLAjUWUr0loL+3+uLeiopcuX vBsv3p/6TFymCjxc/fmkb1Vea87ltdsdcK88+iyHe3JE9SZ2+Jlch4YGJ0r52YiGfjOX Fyig== X-Gm-Message-State: AGi0PuacV3O4qHDZig8hMxfx4yC6c0Sbcj3bnfSkn7PqhzKE63xNxZ3S LqJl/vgL3s6NeWffJYDa6NDBxNcPtRy/ X-Google-Smtp-Source: APiQypLBg1GGiMFfPlg17FEcCKRVmt6v+4y2gDKdWvRmw+vG3FIc7cj+PAjvvloDCJ+3oJL4Z7yXB/3MmNYD X-Received: by 2002:a17:90a:240a:: with SMTP id h10mr521305pje.123.1585784437046; Wed, 01 Apr 2020 16:40:37 -0700 (PDT) Date: Wed, 1 Apr 2020 16:39:45 -0700 In-Reply-To: <20200401233945.133550-1-irogers@google.com> Message-Id: <20200401233945.133550-6-irogers@google.com> Mime-Version: 1.0 References: <20200401233945.133550-1-irogers@google.com> X-Mailer: git-send-email 2.26.0.rc2.310.g2932bb562d-goog Subject: [PATCH 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..64e010689a5f 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 (get_hex(io, start) != '-') + return false; + if (get_hex(io, end) != ' ') + return false; + + /* map protection and flags bits */ + *prot = 0; + ch = get_char(io); + if (ch == 'r') + *prot |= PROT_READ; + else if (ch != '-') + return false; + ch = get_char(io); + if (ch == 'w') + *prot |= PROT_WRITE; + else if (ch != '-') + return false; + ch = get_char(io); + if (ch == 'x') + *prot |= PROT_EXEC; + else if (ch != '-') + return false; + ch = get_char(io); + if (ch == 's') + *flags = MAP_SHARED; + else if (ch == 'p') + *flags = MAP_PRIVATE; + else + return false; + if (get_char(io) != ' ') + return false; + + if (get_hex(io, offset) != ' ') + return false; + + if (get_hex(io, &temp) != ':') + return false; + *maj = temp; + if (get_hex(io, &temp) != ' ') + return false; + *min = temp; + + ch = get_dec(io, inode); + if (ch != ' ') { + *pathname = '\0'; + return ch == '\n'; + } + do { + ch = 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 = 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; } + init_io(&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. */ + strcpy(event->mmap2.filename, ""); + + /* 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