Re: [PATCH] perf annotate: Remove hist__account_cycles from callback

[Jin, Yao]

On 3/14/2019 8:04 PM, Jiri Olsa wrote:
> On Wed, Mar 13, 2019 at 04:22:54AM +0800, Jin Yao wrote:
> > The hist__account_cycles is executed when the hist_iter__branch_callback
> > is called. But it looks it's not necessary. In hist__account_cycles, it
> > already walks on all branch entries.
> >
> > This patch moves the hist__account_cycles out of callback, now the data
> > processing is much faster than before.
> >
> > For example,
> > perf record -b ...
> > perf annotate
> >
> > The before/after output should be no change.
>
> so in the old code it was called multiple times per sample,
> while after your change it's called just once per sample
>
> it increases cycles stats for symbol, so it's strange
> the behaviour is the same.. could you please exaplin this
> in more detail?

In __symbol__account_cycles,
ch[offset].num_aggr++;
ch[offset].cycles_aggr += cycles;

In annotation__compute_ipc,
al = notes->offsets[offset];
al->cycles = ch->cycles_aggr / ch->num_aggr;

So the num_aggr and cycles_aggr are both increased n times, then the 
final result is the same.

> > Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
> > ---
> >   tools/perf/builtin-annotate.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> > index 67f9d9f..77deb3a 100644
> > --- a/tools/perf/builtin-annotate.c
> > +++ b/tools/perf/builtin-annotate.c
> > @@ -159,8 +159,6 @@ static int hist_iter__branch_callback(struct hist_entry_iter *iter,
> >   	struct perf_evsel *evsel = iter->evsel;
> >   	int err;
> >   
> > -	hist__account_cycles(sample->branch_stack, al, sample, false);
> > -
>
> there's similar code in perf report, could you please cover
> that as well?

Sure, let me have a try.

Thanks
Jin Yao

> thanks,
> jirka
>
> >   	bi = he->branch_info;
> >   	err = addr_map_symbol__inc_samples(&bi->from, sample, evsel);
> >   
> > @@ -199,6 +197,8 @@ static int process_branch_callback(struct perf_evsel *evsel,
> >   	if (a.map != NULL)
> >   		a.map->dso->hit = 1;
> >   
> > +	hist__account_cycles(sample->branch_stack, al, sample, false);
> > +
> >   	ret = hist_entry_iter__add(&iter, &a, PERF_MAX_STACK_DEPTH, ann);
> >   	return ret;
> >   }
> > --
> > 2.7.4