On Montag, 5. Oktober 2015 13:08:36 CEST Jiri Olsa wrote: > On Sun, Oct 04, 2015 at 05:38:17PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Sun, Oct 04, 2015 at 05:16:37PM +0200, Milian Wolff escreveu: > > > We cannot reverse the order of the libunwind stepper. To workaround > > > this, we store the IPs in a temporary stack buffer and then walk > > > this buffer in reverse order when callchain_param.order is set to > > > ORDER_CALLER. > > > > > > Signed-off-by: Milian Wolff <[email protected]> > > > > Jiri, > > > > Can you please take a look at this? > > > > - Arnaldo > > > > > Cc: Arnaldo Carvalho de Melo <[email protected]> > > > --- > > > > > > tools/perf/util/unwind-libunwind.c | 21 +++++++++++++++++---- > > > 1 file changed, 17 insertions(+), 4 deletions(-) > > > > > > diff --git a/tools/perf/util/unwind-libunwind.c > > > b/tools/perf/util/unwind-libunwind.c index 4c00507..bf631f1 100644 > > > --- a/tools/perf/util/unwind-libunwind.c > > > +++ b/tools/perf/util/unwind-libunwind.c > > > @@ -621,11 +621,24 @@ static int get_entries(struct unwind_info *ui, > > > unwind_entry_cb_t cb,> > > > > if (ret) > > > > > > display_error(ret); > > > > > > - while (!ret && (unw_step(&c) > 0) && max_stack--) { > > > - unw_word_t ip; > > > + if (callchain_param.order == ORDER_CALLEE) { > > > + while (!ret && (unw_step(&c) > 0) && max_stack--) { > > > + unw_word_t ip; > > > > > > - unw_get_reg(&c, UNW_REG_IP, &ip); > > > - ret = ip ? entry(ip, ui->thread, cb, arg) : 0; > > > + unw_get_reg(&c, UNW_REG_IP, &ip); > > > + ret = ip ? entry(ip, ui->thread, cb, arg) : 0; > > > + } > > > + } else { > > > + unw_word_t ips[max_stack]; > > > + int i = 0; > > > + > > > + while ((unw_step(&c) > 0) && i < max_stack) { > > > + unw_get_reg(&c, UNW_REG_IP, &ips[i]); > > > + ++i; > > > + } > > > + max_stack = i; > > > + for (i = max_stack - 1; i >= 0; --i) > > > + entry(ips[i], ui->thread, cb, arg); > > there's no check for return value of entry callback > > also I wonder would it be better to store into ips[] within > the single loop all the time, and iterate throught it after > forward/backward based on the callchain_param.order > > please check attached patch, totaly untested, probably leaking some index > ;-) > > any chance this could be done also for util/unwind-libdw.c ?
That patch looks much better than mine. I'll try it out later next week and will also have a look at util/unwind-libdw.c. Question: How can I test the behavior of the latter? Do I need to uninstall libunwind, or can I change the unwinder at runtime somehow (env var?). Also, are there unit tests for this behavior somewhere? -- Milian Wolff | [email protected] | Software Engineer KDAB (Deutschland) GmbH&Co KG, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt Experts
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