Re: [PATCH] Account for prologue spills in reg_pressure scheduling

[Richard Sandiford <rdsandiford@googlemail.com>]

Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org> writes:
> [Adding ARM maintainers to CC]
>
> On Oct 21, 2014, at 9:44 AM, Sebastian Pop <sebpop@gmail.com> wrote:
>
>> Hi Maxim,
>> 
>> Maxim Kuvyrkov wrote:
>>> Thanks, benchmarking results are welcome!  AArch64 doesn't use reg_pressure
>>> scheduling by default.  Use "-fsched-pressure
>>> --param=sched-pressure-algorithm=2" to enable same thing as on ARM.  I would
>>> imagine C++ and Fortran floating-point code to be most affected.
>> 
>> On aarch64 I only see perf improvements with your patch: no perf
>> degradations on
>> all the tests that I have run.
>> 
>> base0: r216447, -O3
>> base1: r216447, -O3 -fsched-pressure --param=sched-pressure-algorithm=2
>> patch: r216447 + your patch, -O3 -fsched-pressure
>> --param=sched-pressure-algorithm=2
>> 
>> patch vs. base1 is only an improvement.
>> 
>> base1 vs. base0 has a few good improvements, and some small degradations: your
>> patch improves the perf for one of the degradations to the point it is better
>> now with -fsched-pressure --param=sched-pressure-algorithm=2 than at -O3.
>> 
>> Could we turn on "-fsched-pressure --param=sched-pressure-algorithm=2" by
>> default for aarch64?
>
> These are great results, yay!

+1.  Thanks for running these tests.  If you have time, it'd also be
interesting to try the same thing with --param=sched-pressure-algorithm=1
(which should be equivalent to not having the --param, but better safe
than sorry).  Is algorithm 1 or algorithm 2 better for aarch64?

Thanks,
Richard