On Mon, Oct 26, 2020 at 11:21:28AM +0300, Alexei Budankov wrote: > > On 24.10.2020 18:43, Jiri Olsa wrote: > > On Wed, Oct 21, 2020 at 07:07:00PM +0300, Alexey Budankov wrote: > >> > >> Introduce thread local variable and use it for threaded trace streaming. > >> > >> Signed-off-by: Alexey Budankov <[email protected]> > >> --- > >> tools/perf/builtin-record.c | 71 ++++++++++++++++++++++++++++++++----- > >> 1 file changed, 62 insertions(+), 9 deletions(-) > >> > >> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > >> index 89cb8e913fb3..3b7e9026f25b 100644 > >> --- a/tools/perf/builtin-record.c > >> +++ b/tools/perf/builtin-record.c > >> @@ -101,6 +101,8 @@ struct thread_data { > >> u64 bytes_written; > >> }; > >> > >> +static __thread struct thread_data *thread; > >> + > >> struct record { > >> struct perf_tool tool; > >> struct record_opts opts; > >> @@ -587,7 +589,11 @@ static int record__pushfn(struct mmap *map, void *to, > >> void *bf, size_t size) > >> } > >> } > >> > >> - rec->samples++; > >> + if (thread) > >> + thread->samples++; > >> + else > >> + rec->samples++; > > > > this is really wrong, let's keep just single samples counter > > ditto for all the other places in this patch > > This does look like data parallelism [1] which is very true for > threaded trace streaming so your prototype design looks optimal. > > For this specific place incrementing global counter in memory is > less performant and faces scalability limitations as a number of > cores grow. > > Not sure why you have changed your mind.
I'm not sure I follow.. what I'm complaining about is to have 'samples' stat variable in separate locations for --threads and --no-threads mode jirka > > Alexei > > [1] > https://en.wikipedia.org/wiki/Data_parallelism#:~:text=Data%20parallelism%20is%20parallelization%20across,on%20each%20element%20in%20parallel. >
