On Tue, 18 Nov 2014 16:36:55 -0500, kan liang wrote:
> From: Kan Liang <kan.li...@intel.com>
>
> Currently, there are two call chain recording options, fp and dwarf.
> Haswell has a new feature that utilizes the existing LBR facility to
> record call chains. So it provides the third options to record call
> chain. This patch enables the lbr call stack support.
>
> LBR call stack has some limitations. It reuses current LBR facility, so
> LBR call stack and branch record can not be enabled at the same time. It
> is only available for user callchain.
> However, LBR call stack can work on the user app which doesn't have
> frame-pointer or dwarf debug info compiled. It is a good alternative
> when nothing else works.
[SNIP]
> static void
> -perf_evsel__config_callgraph(struct perf_evsel *evsel)
> +perf_evsel__config_callgraph(struct perf_evsel *evsel,
> + struct record_opts *opts)
> {
> bool function = perf_evsel__is_function_event(evsel);
> struct perf_event_attr *attr = &evsel->attr;
>
> perf_evsel__set_sample_bit(evsel, CALLCHAIN);
>
> + if (callchain_param.record_mode == CALLCHAIN_LBR) {
> + if (!opts->branch_stack) {
> + perf_evsel__set_sample_bit(evsel, BRANCH_STACK);
> + attr->branch_sample_type = PERF_SAMPLE_BRANCH_USER |
> + PERF_SAMPLE_BRANCH_CALL_STACK;
> + if (attr->exclude_user) {
> + attr->exclude_user = 0;
> +
> + pr_warning("LBR callstack option is only
> available"
> + " to get user callchain information."
> + " Force exclude_user to 0.\n");
> + }
I'm not sure what's in a higher priority - maybe I missed earlier
discussion. IOW what about this?
if (attr->exclude_user) {
pr_warning("LBR callstack option is only
available"
" to get user callchain
information.\n");
} else {
perf_evsel__set_sample_bit(evsel, BRANCH_STACK);
attr->branch_sample_type =
PERF_SAMPLE_BRANCH_USER |
PERF_SAMPLE_BRANCH_CALL_STACK;
}
> + } else
> + pr_info("Cannot use LBR callstack with branch
> stack\n");
It seems pr_warning is more appropriate here.
Thanks,
Namhyung
> + }
> +
> if (callchain_param.record_mode == CALLCHAIN_DWARF) {
> if (!function) {
> perf_evsel__set_sample_bit(evsel, REGS_USER);
> @@ -659,7 +676,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct
> record_opts *opts)
> }
>
> if (callchain_param.enabled && !evsel->no_aux_samples)
> - perf_evsel__config_callgraph(evsel);
> + perf_evsel__config_callgraph(evsel, opts);
>
> if (target__has_cpu(&opts->target))
> perf_evsel__set_sample_bit(evsel, CPU);
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