On May 15, 2014, at 6:46 PM, Ramana Radhakrishnan <ramana....@googlemail.com> wrote: > >> >> I'm not claiming it's a great heuristic or anything. There's bound to >> be room for improvement. But it was based on "reality" and real results. >> >> Of course, if it turns out not be a win for ARM or s390x any more then it >> should be disabled. > > The current situation that Kyrill is investigating is a case where we > notice the first scheduler pass being a bit too aggressive with > creating ILP opportunities with the A15 scheduler that causes > performance differences with not turning on the first scheduler pass > vs using the defaults.
Charles has a work-in-progress patch that fixes a bug in SCHED_PRESSURE_MODEL that causes the above symptoms. The bug causes 1st scheduler to unnecessarily increase live ranges of pseudo registers when there are a lot of instructions in the ready list. Charles, can you finish your patch in the next several days and post it for review? Thank you, -- Maxim Kuvyrkov www.linaro.org
