Messages in this thread |  | | Date | Fri, 27 Mar 2020 14:23:58 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf synthetic-events: save 4kb from 2 stack frames |
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On Thu, Mar 26, 2020 at 11:36:51PM -0700, Ian Rogers wrote: > Reduce the scope of PATH_MAX sized char buffers so that the compiler can > overlap their usage. > > 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'.
nice catch.. is this actualy problem somewhere? I thought we don't need to care that much about this in user space
jirka
> > Signed-off-by: Ian Rogers <irogers@google.com> > --- > tools/perf/util/synthetic-events.c | 46 ++++++++++++++++++------------ > 1 file changed, 27 insertions(+), 19 deletions(-) > > diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c > index 3f28af39f9c6..9ff54707bb30 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; > @@ -80,12 +79,16 @@ 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); > + { > + char filename[PATH_MAX]; > > - fd = open(filename, O_RDONLY); > - if (fd < 0) { > - pr_debug("couldn't open %s\n", filename); > - return -1; > + snprintf(filename, sizeof(filename), "/proc/%d/status", pid); > + > + fd = open(filename, O_RDONLY); > + if (fd < 0) { > + pr_debug("couldn't open %s\n", filename); > + return -1; > + } > } > > n = read(fd, bf, sizeof(bf) - 1); > @@ -280,7 +283,6 @@ 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; > bool truncation = false; > @@ -292,18 +294,22 @@ 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); > +#define FILENAME_FMT_STRING "%s/proc/%d/task/%d/maps" > + { > + char filename[PATH_MAX]; > > - fp = fopen(filename, "r"); > - if (fp == NULL) { > - /* > - * We raced with a task exiting - just return: > - */ > - pr_debug("couldn't open %s\n", filename); > - return -1; > - } > + snprintf(filename, sizeof(filename), FILENAME_FMT_STRING, > + machine->root_dir, pid, pid); > > + fp = fopen(filename, "r"); > + if (fp == NULL) { > + /* > + * We raced with a task exiting - just return: > + */ > + pr_debug("couldn't open %s\n", filename); > + return -1; > + } > + } > event->header.type = PERF_RECORD_MMAP2; > t = rdclock(); > > @@ -320,10 +326,10 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > break; > > if ((rdclock() - t) > timeout) { > - pr_warning("Reading %s time out. " > + pr_warning("Reading " FILENAME_FMT_STRING " 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; > } > @@ -412,6 +418,8 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > > fclose(fp); > return rc; > + > +#undef FILENAME_FMT_STRING > } > > int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t process, > -- > 2.25.1.696.g5e7596f4ac-goog >
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