Messages in this thread Patch in this message | | | Date | Wed, 13 May 2020 16:30:23 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 00/13] Reconcile NUMA balancing decisions with the load balancer v6 |
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On Wed, May 13, 2020 at 04:57:15PM +0200, Jirka Hladky wrote: > Hi Mel, > > we have tried the kernel with adjust_numa_imbalance() crippled to just > return the imbalance it's given. > > It has solved all the performance problems I have reported. > Performance is the same as with 5.6 kernel (before the patch was > applied). > > * solved the performance drop upto 20% with single instance > SPECjbb2005 benchmark on 8 NUMA node servers (particularly on AMD EPYC > Rome systems) => this performance drop was INCREASING with higher > threads counts (10% for 16 threads and 20 % for 32 threads) > * solved the performance drop for low load scenarios (SPECjvm2008 and NAS) > > Any suggestions on how to proceed? One approach is to turn > "imbalance_min" into the kernel tunable. Any other ideas? > > https://github.com/torvalds/linux/blob/4f8a3cc1183c442daee6cc65360e3385021131e4/kernel/sched/fair.c#L8914 >
Complete shot in the dark but restore adjust_numa_imbalance() and try this
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1a9983da4408..0b31f4468d5b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2393,7 +2393,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) struct rq_flags rf; #if defined(CONFIG_SMP) - if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { + if (sched_feat(TTWU_QUEUE)) { sched_clock_cpu(cpu); /* Sync clocks across CPUs */ ttwu_queue_remote(p, cpu, wake_flags); return; -- Mel Gorman SUSE Labs
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