Messages in this thread Patch in this message | | | From | Srikar Dronamraju <> | Subject | [PATCH 5/6] sched/numa: Reset scan rate whenever task moves across nodes | Date | Fri, 3 Aug 2018 11:44:00 +0530 |
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Currently task scan rate is reset when numa balancer migrates the task to a different node. If numa balancer initiates a swap, reset is only applicable to the task that initiates the swap. Similarly no scan rate reset is done if the task is migrated across nodes by traditional load balancer.
Instead move the scan reset to the migrate_task_rq. This ensures the task moved out of its preferred node, either gets back to its preferred node quickly or finds a new preferred node. Doing so, would be fair to all tasks migrating across nodes.
specjbb2005 / bops/JVM / higher bops are better on 2 Socket/2 Node Intel JVMS Prev Current %Change 4 210118 208862 -0.597759 1 313171 307007 -1.96825
on 2 Socket/4 Node Power8 (PowerNV) JVMS Prev Current %Change 8 91027.5 89911.4 -1.22611 1 216460 216176 -0.131202
on 2 Socket/2 Node Power9 (PowerNV) JVMS Prev Current %Change 4 191918 196078 2.16759 1 207043 214664 3.68088
on 4 Socket/4 Node Power7 JVMS Prev Current %Change 8 58462.1 60719.2 3.86079 1 108334 112615 3.95167
dbench / transactions / higher numbers are better on 2 Socket/2 Node Intel count Min Max Avg Variance %Change 5 11851.8 11937.3 11890.9 33.5169 5 12511.7 12559.4 12539.5 15.5883 5.45459
on 2 Socket/4 Node Power8 (PowerNV) count Min Max Avg Variance %Change 5 4791 5016.08 4962.55 85.9625 5 4709.28 4979.28 4919.32 105.126 -0.871125
on 2 Socket/2 Node Power9 (PowerNV) count Min Max Avg Variance %Change 5 9353.43 9380.49 9369.6 9.04361 5 9388.38 9406.29 9395.1 5.98959 0.272157
on 4 Socket/4 Node Power7 count Min Max Avg Variance %Change 5 149.518 215.412 179.083 21.5903 5 157.71 184.929 174.754 10.7275 -2.41731
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> --- kernel/sched/fair.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a5936ed..4ea0eff 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1837,12 +1837,6 @@ static int task_numa_migrate(struct task_struct *p) if (env.best_cpu == -1) return -EAGAIN; - /* - * Reset the scan period if the task is being rescheduled on an - * alternative node to recheck if the tasks is now properly placed. - */ - p->numa_scan_period = task_scan_start(p); - best_rq = cpu_rq(env.best_cpu); if (env.best_task == NULL) { ret = migrate_task_to(p, env.best_cpu); @@ -6361,6 +6355,19 @@ static void migrate_task_rq_fair(struct task_struct *p, int new_cpu __maybe_unus /* We have migrated, no longer consider this task hot */ p->se.exec_start = 0; + +#ifdef CONFIG_NUMA_BALANCING + if (!p->mm || (p->flags & PF_EXITING)) + return; + + if (p->numa_faults) { + int src_nid = cpu_to_node(task_cpu(p)); + int dst_nid = cpu_to_node(new_cpu); + + if (src_nid != dst_nid) + p->numa_scan_period = task_scan_start(p); + } +#endif } static void task_dead_fair(struct task_struct *p) -- 1.8.3.1
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