On Fri, Jul 09, 2021 at 11:26:53AM +0100, Robin Murphy wrote: > On 2021-07-09 09:38, Ming Lei wrote: > > Hello, > > > > I observed that NVMe performance is very bad when running fio on one > > CPU(aarch64) in remote numa node compared with the nvme pci numa node. > > > > Please see the test result[1] 327K vs. 34.9K. > > > > Latency trace shows that one big difference is in iommu_dma_unmap_sg(), > > 1111 nsecs vs 25437 nsecs. > > Are you able to dig down further into that? iommu_dma_unmap_sg() itself > doesn't do anything particularly special, so whatever makes a difference is > probably happening at a lower level, and I suspect there's probably an SMMU > involved. If for instance it turns out to go all the way down to > __arm_smmu_cmdq_poll_until_consumed() because polling MMIO from the wrong > node is slow, there's unlikely to be much you can do about that other than > the global "go faster" knobs (iommu.strict and iommu.passthrough) with their > associated compromises.
Follows the log of 'perf report'
1) good(run fio from cpus in the nvme's numa node)
- 34.86% 1.73% fio [nvme] [k] nvme_process_cq
▒
- 33.13% nvme_process_cq
▒
- 32.93% nvme_pci_complete_rq
▒
- 24.92% nvme_unmap_data
▒
- 20.08% dma_unmap_sg_attrs
▒
- 19.79% iommu_dma_unmap_sg
▒
- 19.55% __iommu_dma_unmap
▒
- 16.86% arm_smmu_iotlb_sync
▒
- 16.81% arm_smmu_tlb_inv_range_domain
▒
- 14.73% __arm_smmu_tlb_inv_range
▒
14.44% arm_smmu_cmdq_issue_cmdlist
▒
0.89% __pi_memset
▒
0.75% arm_smmu_atc_inv_domain
▒
+ 1.58% iommu_unmap_fast
▒
+ 0.71% iommu_dma_free_iova
▒
- 3.25% dma_unmap_page_attrs
▒
- 3.21% iommu_dma_unmap_page
▒
- 3.14% __iommu_dma_unmap_swiotlb
▒
- 2.86% __iommu_dma_unmap
▒
- 2.48% arm_smmu_iotlb_sync
▒
- 2.47% arm_smmu_tlb_inv_range_domain
▒
- 2.19% __arm_smmu_tlb_inv_range
▒
2.16% arm_smmu_cmdq_issue_cmdlist
▒
+ 1.34% mempool_free
▒
+ 7.68% nvme_complete_rq
▒
+ 1.73% _start
2) bad(run fio from cpus not in the nvme's numa node)
- 49.25% 3.03% fio [nvme] [k] nvme_process_cq
▒
- 46.22% nvme_process_cq
▒
- 46.07% nvme_pci_complete_rq
▒
- 41.02% nvme_unmap_data
▒
- 34.92% dma_unmap_sg_attrs
▒
- 34.75% iommu_dma_unmap_sg
▒
- 34.58% __iommu_dma_unmap
▒
- 33.04% arm_smmu_iotlb_sync
▒
- 33.00% arm_smmu_tlb_inv_range_domain
▒
- 31.86% __arm_smmu_tlb_inv_range
▒
31.71% arm_smmu_cmdq_issue_cmdlist
▒
+ 0.90% iommu_unmap_fast
▒
- 5.17% dma_unmap_page_attrs
▒
- 5.15% iommu_dma_unmap_page
▒
- 5.12% __iommu_dma_unmap_swiotlb
▒
- 5.05% __iommu_dma_unmap
▒
- 4.86% arm_smmu_iotlb_sync
▒
- 4.85% arm_smmu_tlb_inv_range_domain
▒
- 4.70% __arm_smmu_tlb_inv_range
▒
4.67% arm_smmu_cmdq_issue_cmdlist
▒
+ 0.74% mempool_free
▒
+ 4.83% nvme_complete_rq
▒
+ 3.03% _start
Thanks,
Ming
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