Re: [PATCH 5/8] perf tools: Get precise_ip from the pmu config

Jiri Olsa
2019-03-05T16:29:00Z

On Tue, Mar 05, 2019 at 08:13:19AM -0800, Andi Kleen wrote:
> On Tue, Mar 05, 2019 at 04:25:33PM +0100, Jiri Olsa wrote:
> > Getting precise_ip field from the perf_pmu::max_precise
> > config read from sysfs. If it's not available falling
> > back to current detection function.
>
> max_precise depends on the event. This won't work for all
> events. For example only instructions and cycles support
> ppp

I'm getting precise_ip=3 on mem-* events as well, that's why I
was fixing this.. now it's not working for any event

>
> The previous method handled it by event.

how about we use empty template with just type/config
of the original event, like in the change below,
that way we eliminate unsupported features failing
the probing.. maybe we could use oldest attr version

also if precise_ip is event based, we shouldn't use the
caps/max_precise then

jirka

---
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index ed20f4379956..cee2f83feb89 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -233,8 +233,8 @@ void perf_evlist__set_leader(struct perf_evlist *evlist)
void perf_event_attr__set_max_precise_ip(struct perf_event_attr *pattr)
{
struct perf_event_attr attr = {
- .type = PERF_TYPE_HARDWARE,
- .config = PERF_COUNT_HW_CPU_CYCLES,
+ .type = pattr->type,
+ .config = pattr->config,
.exclude_kernel = 1,
.precise_ip = 3,
};