Re: [PATCH v3 3/4] perf stat: Copy counts from prev_raw_counts to evsel->counts

[Jiri Olsa <jolsa@redhat.com>]

On Thu, May 07, 2020 at 02:58:21PM +0800, Jin Yao wrote:
> It would be useful to support the overall statistics for perf-stat
> interval mode. For example, report the summary at the end of
> "perf-stat -I" output.
> 
> But since perf-stat can support many aggregation modes, such as
> --per-thread, --per-socket, -M and etc, we need a solution which
> doesn't bring much complexity.
> 
> The idea is to use 'evsel->prev_raw_counts' which is updated in
> each interval and it's saved with the latest counts. Before reporting
> the summary, we copy the counts from evsel->prev_raw_counts to
> evsel->counts, and next we just follow non-interval processing.

I did not realize we already store the count in prev_raw_counts ;-) nice catch!

> 
> In evsel__compute_deltas, this patch saves counts to the position
> of [cpu0,thread0] for AGGR_GLOBAL. After copying counts from
> evsel->prev_raw_counts to evsel->counts, we don't need to
> modify process_counter_maps in perf_stat_process_counter to let it
> work well.

I don't understand why you need to store it in here.. what's the catch
in process_counter_maps?

thanks,
jirka