On Wed, Oct 28, 2020 at 05:56:32PM +0900, Namhyung Kim wrote: > When perf data is in a pipe, it reads each event separately using > read(2) syscall. This is a huge performance bottleneck when > processing large data like in perf inject. Also perf inject needs to > use write(2) syscall for the output. > > So convert it to use buffer I/O functions in stdio library for pipe > data. This makes inject-build-id bench time drops from 20ms to 8ms. > > $ perf bench internals inject-build-id > # Running 'internals/inject-build-id' benchmark: > Average build-id injection took: 8.074 msec (+- 0.013 msec) > Average time per event: 0.792 usec (+- 0.001 usec) > Average memory usage: 8328 KB (+- 0 KB) > Average build-id-all injection took: 5.490 msec (+- 0.008 msec) > Average time per event: 0.538 usec (+- 0.001 usec) > Average memory usage: 7563 KB (+- 0 KB) > > This patch enables it just for perf inject when used with pipe (it's a > default behavior). Maybe we could do it for perf record and/or report > later.. > > Signed-off-by: Namhyung Kim <[email protected]> > --- > tools/perf/builtin-inject.c | 2 ++ > tools/perf/util/data.c | 36 +++++++++++++++++++++++++++++++++--- > tools/perf/util/data.h | 11 ++++++++++- > tools/perf/util/header.c | 8 ++++---- > tools/perf/util/session.c | 7 ++++--- > 5 files changed, 53 insertions(+), 11 deletions(-) > > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c > index 452a75fe68e5..14d6c88fed76 100644 > --- a/tools/perf/builtin-inject.c > +++ b/tools/perf/builtin-inject.c > @@ -853,10 +853,12 @@ int cmd_inject(int argc, const char **argv) > .output = { > .path = "-", > .mode = PERF_DATA_MODE_WRITE, > + .use_stdio = true, > }, > }; > struct perf_data data = { > .mode = PERF_DATA_MODE_READ, > + .use_stdio = true, > }; > int ret; > > diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c > index c47aa34fdc0a..47b5a4b50ca5 100644 > --- a/tools/perf/util/data.c > +++ b/tools/perf/util/data.c > @@ -174,8 +174,16 @@ static bool check_pipe(struct perf_data *data) > is_pipe = true; > } > > - if (is_pipe) > - data->file.fd = fd; > + if (is_pipe) { > + if (data->use_stdio) { > + const char *mode; > + > + mode = perf_data__is_read(data) ? "r" : "w"; > + data->file.fptr = fdopen(fd, mode);
I guess fdopen should never fail right? but I think we should add BUG_ON(data->file.fptr == NULL) or something other than this the change looks good, I can see the speedup in bench as well jirka
