On Mon, Oct 22, 2018 at 12:09:22PM +0200, Milian Wolff wrote: > On Montag, 22. Oktober 2018 11:43:17 CEST Jiri Olsa wrote: > > On Sun, Oct 21, 2018 at 09:14:24PM +0200, Milian Wolff wrote: > > > When the perf script output is written to a terminal stream, > > > the normal output of `perf script` would get buffered, but its > > > debug output would be written directly. This made it quite hard > > > to figure out where a given debug output is coming from. We can > > > improve on this by flushing the output buffer after processing an > > > event. To see the value, compare the following output for a > > > `perf script -v` run: > > > > > > Before this patch: > > > ``` > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > ... lots and lots of verbose debug output > > > > > > cpp-inlining 24617 90229.122036534: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > cpp-inlining 24617 90229.122043974: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > ... > > > ``` > > > > > > After this patch: > > > ``` > > > ... > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > > > > cpp-inlining 24617 90229.122036534: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > > > > cpp-inlining 24617 90229.122043974: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > ... > > > ``` > > > > > > This new output format makes it much easier to use perf script > > > output for debugging purposes, e.g. to investigate broken dwarf > > > unwinding. > > > > yep, I plan to check on this ;-) > > > > > Signed-off-by: Milian Wolff <milian.wo...@kdab.com> > > > Cc: Arnaldo Carvalho de Melo <a...@kernel.org> > > > --- > > > > > > tools/perf/builtin-script.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c > > > index bd468b90801b..ca09b7d2adb7 100644 > > > --- a/tools/perf/builtin-script.c > > > +++ b/tools/perf/builtin-script.c > > > @@ -1737,6 +1737,9 @@ static void process_event(struct perf_script > > > *script, > > > > > > if (PRINT_FIELD(METRIC)) > > > > > > perf_sample__fprint_metric(script, thread, evsel, sample, fp); > > > > > > + > > > + if (verbose) > > > + fflush(fp); > > > > should we call fflush(NULL) to dump all the streams? > > > > the verbose goes to stderr and fp seems to be stdout byt default > > stderr isn't buffered, so we don't need to flush it. So personally, I don't > see a need to dump all streams - fp should be enough? Can you maybe explain > where it would be required to flush more buffers?
hum, did not know stderr wasn't buffer I think there's perf script feature to store the events data to separate files per each event.. but I guess we don't need to flush them.. we just need to have stdout and stderr in sync IIUC jirka
