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? Thanks -- Milian Wolff | milian.wo...@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts
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