From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Rogers Subject: [PATCH 3/5] perf synthetic-events: save 4kb from 2 stack frames Date: Wed, 1 Apr 2020 16:39:43 -0700 Message-ID: <20200401233945.133550-4-irogers@google.com> References: <20200401233945.133550-1-irogers@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20200401233945.133550-1-irogers@google.com> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-perf-users.vger.kernel.org Reuse an existing char buffer to avoid two PATH_MAX sized char buffers. Reduces stack frame sizes by 4kb. perf_event__synthesize_mmap_events before 'sub $0x45b8,%rsp' after 'sub $0x35b8,%rsp'. perf_event__get_comm_ids before 'sub $0x2028,%rsp' after 'sub $0x1028,%rsp'. The performance impact of this change is negligible. Signed-off-by: Ian Rogers --- tools/perf/util/synthetic-events.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 3f28af39f9c6..1f3d8d4bb879 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -70,7 +70,6 @@ int perf_tool__process_synth_event(struct perf_tool *tool, static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, pid_t *tgid, pid_t *ppid) { - char filename[PATH_MAX]; char bf[4096]; int fd; size_t size = 0; @@ -80,11 +79,11 @@ static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, *tgid = -1; *ppid = -1; - snprintf(filename, sizeof(filename), "/proc/%d/status", pid); + snprintf(bf, sizeof(bf), "/proc/%d/status", pid); - fd = open(filename, O_RDONLY); + fd = open(bf, O_RDONLY); if (fd < 0) { - pr_debug("couldn't open %s\n", filename); + pr_debug("couldn't open %s\n", bf); return -1; } @@ -280,9 +279,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, struct machine *machine, bool mmap_data) { - char filename[PATH_MAX]; FILE *fp; unsigned long long t; + char bf[BUFSIZ]; bool truncation = false; unsigned long long timeout = proc_map_timeout * 1000000ULL; int rc = 0; @@ -292,15 +291,15 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, if (machine__is_default_guest(machine)) return 0; - snprintf(filename, sizeof(filename), "%s/proc/%d/task/%d/maps", - machine->root_dir, pid, pid); + snprintf(bf, sizeof(bf), "%s/proc/%d/task/%d/maps", + machine->root_dir, pid, pid); - fp = fopen(filename, "r"); + fp = fopen(bf, "r"); if (fp == NULL) { /* * We raced with a task exiting - just return: */ - pr_debug("couldn't open %s\n", filename); + pr_debug("couldn't open %s\n", bf); return -1; } @@ -308,7 +307,6 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, t = rdclock(); while (1) { - char bf[BUFSIZ]; char prot[5]; char execname[PATH_MAX]; char anonstr[] = "//anon"; @@ -320,10 +318,10 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, break; if ((rdclock() - t) > timeout) { - pr_warning("Reading %s time out. " + pr_warning("Reading %s/proc/%d/task/%d/maps time out. " "You may want to increase " "the time limit by --proc-map-timeout\n", - filename); + machine->root_dir, pid, pid); truncation = true; goto out; } -- 2.26.0.rc2.310.g2932bb562d-goog