During our torturing on numa stuff, we found problems like: * missing per-cgroup information about the per-node execution status * missing per-cgroup information about the numa locality That is when we have a cpu cgroup running with bunch of tasks, no good way to tell how it's tasks are dealing with numa. The first two patches are trying to complete the missing pieces, but more problems appeared after monitoring these status: * tasks not always running on the preferred numa node * tasks from same cgroup running on different nodes The task numa group handler will always check if tasks are sharing pages and try to pack them into a single numa group, so they will have chance to settle down on the same node, but this failed in some cases: * workloads share page caches rather than share mappings * workloads got too many wakeup across nodes Since page caches are not traced by numa balancing, there are no way to realize such kind of relationship, and when there are too many wakeup, task will be drag from the preferred node and then migrate back by numa balancing, repeatedly. Here the third patch try to address the first issue, we could now give hint to kernel about the relationship of tasks, and pack them into single numa group. And the forth patch introduced numa cling, which try to address the wakup issue, now we try to make task stay on the preferred node on wakeup in fast path, in order to address the unbalancing risk, we monitoring the numa migration failure ratio, and pause numa cling when it reach the specified degree. Michael Wang (4): numa: introduce per-cgroup numa balancing locality statistic numa: append per-node execution info in memory.numa_stat numa: introduce numa group per task group numa: introduce numa cling feature include/linux/memcontrol.h | 37 ++++ include/linux/sched.h | 8 +- include/linux/sched/sysctl.h | 3 + kernel/sched/core.c | 37 ++++ kernel/sched/debug.c | 7 + kernel/sched/fair.c | 455 ++++++++++++++++++++++++++++++++++++++++++- kernel/sched/sched.h | 14 ++ kernel/sysctl.c | 9 + mm/memcontrol.c | 66 +++++++ 9 files changed, 628 insertions(+), 8 deletions(-) -- 2.14.4.44.g2045bb6
