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Re: [PATCH] Account for prologue spills in reg_pressure scheduling
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: Maxim Kuvyrkov <maxim dot kuvyrkov at linaro dot org>
- Cc: Sebastian Pop <sebpop at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Vladimir Makarov <vmakarov at redhat dot com>, Ramana Radhakrishnan <ramana dot radhakrishnan at arm dot com>, Marcus Shawcroft <marcus dot shawcroft at arm dot com>, Richard Earnshaw <rearnsha at arm dot com>
- Date: Mon, 20 Oct 2014 22:17:45 +0100
- Subject: Re: [PATCH] Account for prologue spills in reg_pressure scheduling
- Authentication-results: sourceware.org; auth=none
- References: <FE7CEF4D-A27B-46D0-96B3-3569C1558DF9 at linaro dot org> <20141020191105 dot GB30024 at f1 dot c dot bardezibar dot internal> <ED2138EC-B4EA-4BBA-AC29-5B5A3B628A9F at linaro dot org> <20141020204417 dot GA7213 at f1 dot c dot bardezibar dot internal> <183D9AE9-ADFE-4E20-A8FF-B323A631FCC4 at linaro dot org>
Maxim Kuvyrkov <firstname.lastname@example.org> writes:
> [Adding ARM maintainers to CC]
> On Oct 21, 2014, at 9:44 AM, Sebastian Pop <email@example.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
>> 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?