On Mon, Aug 15, 2016 at 09:33:49AM +0100, Mel Gorman wrote: > On Mon, Aug 15, 2016 at 09:49:05AM +0200, Giovanni Gherdovich wrote: > > > mmtest benchmark results are below (full compare-kernels.sh output is in > > > attachment): > > > > > > vanila-4.7 revert prefetch patch > > > 4.74 ( 0.00%) 3.04 ( 35.93%) 4.09 ( 13.81%) 1.30 ( > > > 72.59%) > > > 5.49 ( 0.00%) 5.00 ( 8.97%) 5.34 ( 2.72%) 1.03 ( > > > 81.16%) > > > 6.12 ( 0.00%) 4.91 ( 19.73%) 5.97 ( 2.40%) 0.90 ( > > > 85.27%) > > > 6.68 ( 0.00%) 4.90 ( 26.66%) 6.02 ( 9.75%) 0.88 ( > > > 86.89%) > > > 7.21 ( 0.00%) 5.13 ( 28.85%) 6.70 ( 7.09%) 0.87 ( > > > 87.91%) > > > 7.66 ( 0.00%) 5.22 ( 31.80%) 7.17 ( 6.39%) 0.92 ( > > > 88.01%) > > > 7.91 ( 0.00%) 5.36 ( 32.22%) 7.30 ( 7.72%) 0.95 ( > > > 87.97%) > > > 7.95 ( 0.00%) 5.35 ( 32.73%) 7.34 ( 7.66%) 1.06 ( > > > 86.66%) > > > 8.00 ( 0.00%) 5.33 ( 33.31%) 7.38 ( 7.73%) 1.13 ( > > > 85.82%) > > > 5.61 ( 0.00%) 3.55 ( 36.76%) 4.53 ( 19.23%) 2.29 ( > > > 59.28%) > > > 5.66 ( 0.00%) 4.32 ( 23.79%) 4.75 ( 16.18%) 3.65 ( > > > 35.46%) > > > 5.98 ( 0.00%) 4.97 ( 16.87%) 5.96 ( 0.35%) 3.62 ( > > > 39.40%) > > > 6.58 ( 0.00%) 4.94 ( 24.93%) 6.04 ( 8.32%) 3.63 ( > > > 44.89%) > > > 7.19 ( 0.00%) 5.18 ( 28.01%) 6.68 ( 7.13%) 3.65 ( > > > 49.22%) > > > 7.67 ( 0.00%) 5.27 ( 31.29%) 7.16 ( 6.63%) 3.62 ( > > > 52.76%) > > > 7.88 ( 0.00%) 5.36 ( 31.98%) 7.28 ( 7.58%) 3.65 ( > > > 53.71%) > > > 7.99 ( 0.00%) 5.39 ( 32.52%) 7.40 ( 7.42%) 3.65 ( > > > 54.25%) > > > > > > Patch works because we we update sum_exec_runtime on current thread > > > what assure we see proper sum_exec_runtime value on different CPUs. I > > > tested it with reproducers from commits 6e998916dfe32 and d670ec13178d0, > > > patch did not break them. I'm going to run some other test. > > > > > > Patch is draft version for early review, task_sched_runtime() will be > > > simplified (since it's called only current thread) and possibly split > > > into two functions: one that call update_curr() and other that return > > > sum_exec_runtime (assure it's consistent on 32 bit arches). > > > > > > Stanislaw > > > > Is this really equivalent though? It updates one task instead of all > tasks in the group and there is no guarantee that tsk == current.
Oh, my intention was to update runtime on current. > Glancing at it, it should monotonically increase but it looks like it > would calculate stale data. Yes, until the next tick on a CPU, the patch does not count partial runtime of thread running on that CPU. However that was the behaviour before commit d670ec13178d0 - that how old thread_group_sched_runtime() function worked: /* - * Return sum_exec_runtime for the thread group. - * In case the task is currently running, return the sum plus current's - * pending runtime that have not been accounted yet. - * - * Note that the thread group might have other running tasks as well, - * so the return value not includes other pending runtime that other - * running tasks might have. - */ -unsigned long long thread_group_sched_runtime(struct task_struct *p) Stanislaw
