On Thu, Sep 26, 2019 at 1:24 AM Tim Chen <[email protected]> wrote: > > On 9/24/19 7:40 PM, Aubrey Li wrote: > > On Sat, Sep 7, 2019 at 2:30 AM Tim Chen <[email protected]> wrote: > >> +static inline s64 core_sched_imbalance_delta(int src_cpu, int dst_cpu, > >> + int src_sibling, int dst_sibling, > >> + struct task_group *tg, u64 task_load) > >> +{ > >> + struct sched_entity *se, *se_sibling, *dst_se, *dst_se_sibling; > >> + s64 excess, deficit, old_mismatch, new_mismatch; > >> + > >> + if (src_cpu == dst_cpu) > >> + return -1; > >> + > >> + /* XXX SMT4 will require additional logic */ > >> + > >> + se = tg->se[src_cpu]; > >> + se_sibling = tg->se[src_sibling]; > >> + > >> + excess = se->avg.load_avg - se_sibling->avg.load_avg; > >> + if (src_sibling == dst_cpu) { > >> + old_mismatch = abs(excess); > >> + new_mismatch = abs(excess - 2*task_load); > >> + return old_mismatch - new_mismatch; > >> + } > >> + > >> + dst_se = tg->se[dst_cpu]; > >> + dst_se_sibling = tg->se[dst_sibling]; > >> + deficit = dst_se->avg.load_avg - dst_se_sibling->avg.load_avg; > >> + > >> + old_mismatch = abs(excess) + abs(deficit); > >> + new_mismatch = abs(excess - (s64) task_load) + > >> + abs(deficit + (s64) task_load); > > > > If I understood correctly, these formulas made an assumption that the task > > being moved to the destination is matched the destination's core cookie. > > That's not the case. We do not need to match the destination's core cookie,
I actually meant destination core's core cookie. > as that may change after context switches. It needs to reduce the load > mismatch > with the destination CPU's sibling for that cgroup. So the new_mismatch is not always true, especially when there are more cgroups and more core cookies on the system. Thanks, -Aubrey
