Ramana Radhakrishnan wrote: > We already have sched-pressure --param=sched-pressure-algorithm=1 on > by default in the AArch64 backend from September. > https://gcc.gnu.org/ml/gcc-patches/2014-09/msg01663.html went in a few > days back. > > So if this patch is on then we are looking at uplifts with > sched-pressure-algorithm=2 patch and --param
Right: I ran "-O3" vs. "-O3 -fsched-pressure --param=sched-pressure-algorithm=1" and the numbers are identical. > sched-pressure-algorithm=2. To a large degree turning on algorithm #2 > is a benchmarking exercise and IMHO should happen along with the > sched-pressure tweaks that you are currently doing. I would suggest > moving to the same algorithm as the ARM backend would be nice and if > we can deal with any performance regressions that appear. However > without seeing behaviour on some more benchmarks like SPEC2k(6) it > would be unwise to switch this on by default . We can run this and let > you know the results, though SPECFP2k6 takes quite a while - are all > your patches to sched-pressure now done ? > > >> > >> 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? When testing Maxim's patch + --param=sched-pressure-algorithm=1 I see more perf degradations than speedups. > Sebastian's results indicate algorithm #2 + Maxim's patches are better > but we probably need some more benchmarking. Overall algorithm #2 produces better results than algorithm #1. Maxim's patch is nicely improving the perf of algorithm #2. Thanks, Sebastian
