The current automatic NUMA balancing code base has issues with workloads that do not fit on one NUMA load. Page migration is slowed down, but memory distribution between the nodes where the workload runs is essentially random, often resulting in a suboptimal amount of memory bandwidth being available to the workload. In order to maximize performance of workloads that do not fit in one NUMA node, we want to satisfy the following criteria: 1) keep private memory local to each thread 2) avoid excessive NUMA migration of pages 3) distribute shared memory across the active nodes, to maximize memory bandwidth available to the workload This patch series identifies the NUMA nodes on which the workload is actively running, and balances (somewhat lazily) the memory between those nodes, satisfying the criteria above. As usual, the series has had some performance testing, but it could always benefit from more testing, on other systems. Changes since v4: - remove some code that did not help performance - implement all the cleanups suggested by Mel Gorman - lots more testing, by Chegu Vinod and myself - rebase against -tip instead of -next, to make merging easier Changes since v3: - various code cleanups suggested by Mel Gorman (some in their own patches) - after some testing, switch back to the NUMA specific CPU use stats, since that results in a 1% performance increase for two 8-warehouse specjbb instances on a 4-node system, and reduced page migration across the board Changes since v2: - dropped tracepoint (for now?) - implement obvious improvements suggested by Peter - use the scheduler maintained CPU use statistics, drop the NUMA specific ones for now. We can add those later if they turn out to be beneficial Changes since v1: - fix divide by zero found by Chegu Vinod - improve comment, as suggested by Peter Zijlstra - do stats calculations in task_numa_placement in local variables Some performance numbers, with two 40-warehouse specjbb instances on an 8 node system with 10 CPU cores per node, using a pre-cleanup version of these patches, courtesy of Chegu Vinod: numactl manual pinning spec1.txt: throughput = 755900.20 SPECjbb2005 bops spec2.txt: throughput = 754914.40 SPECjbb2005 bops NO-pinning results (Automatic NUMA balancing, with patches) spec1.txt: throughput = 706439.84 SPECjbb2005 bops spec2.txt: throughput = 729347.75 SPECjbb2005 bops NO-pinning results (Automatic NUMA balancing, without patches) spec1.txt: throughput = 667988.47 SPECjbb2005 bops spec2.txt: throughput = 638220.45 SPECjbb2005 bops No Automatic NUMA and NO-pinning results spec1.txt: throughput = 544120.97 SPECjbb2005 bops spec2.txt: throughput = 453553.41 SPECjbb2005 bops -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
