On Sat, Oct 18, 2014 at 3:27 PM, Jan Hubicka <hubi...@ucw.cz> wrote:
>> The difference in instrumentation runtime is huge -- as topn profiler
>> is pretty expensive to run.
>>
>> With FDO, it is probably better to make early inlining more aggressive
>> in order to get more context sensitive profiling.
>
> I agree with that, I just would like to understand where increasing the
> iterations
> helps and if we can handle it without iterating (because Richi originally
> requested to
> drop the iteration for correcness issues)
> Do you have some examples?
We can do FDO experiment by shutting down einline. (Note that
increasing iteration to 2 did not actually improve performance with
our benchmarks).
David
> Honza
>>
>> David
>>
>> On Sat, Oct 18, 2014 at 10:05 AM, Jan Hubicka <hubi...@ucw.cz> wrote:
>> >> Increasing the number of early inliner iterations from 1 to 2 enables more
>> >> indirect calls to be promoted/inlined before instrumentation. This in turn
>> >> reduces the instrumentation overhead, particularly for more expensive
>> >> indirect
>> >> call topn profiling.
>> >
>> > How much difference you get here? One posibility would be also to run
>> > specialized
>> > ipa-cp before profile instrumentation.
>> >
>> > Honza
>> >>
>> >> Passes internal testing and regression tests. Ok for google/4_9?
>> >>
>> >> 2014-10-18 Teresa Johnson <tejohn...@google.com>
>> >>
>> >> Google ref b/17934523
>> >> * opts.c (finish_options): Increase max-early-inliner-iterations
>> >> to 2
>> >> for profile-gen and profile-use builds.
>> >>
>> >> Index: opts.c
>> >> ===================================================================
>> >> --- opts.c (revision 216286)
>> >> +++ opts.c (working copy)
>> >> @@ -870,6 +869,14 @@ finish_options (struct gcc_options *opts, struct g
>> >> opts->x_param_values, opts_set->x_param_values);
>> >> }
>> >>
>> >> + if (opts->x_profile_arc_flag
>> >> + || opts->x_flag_branch_probabilities)
>> >> + {
>> >> + maybe_set_param_value
>> >> + (PARAM_EARLY_INLINER_MAX_ITERATIONS, 2,
>> >> + opts->x_param_values, opts_set->x_param_values);
>> >> + }
>> >> +
>> >> if (!(opts->x_flag_auto_profile
>> >> || (opts->x_profile_arc_flag ||
>> >> opts->x_flag_branch_probabilities)))
>> >> {
>> >>
>> >>
>> >> --
>> >> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
