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X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, While using iperf on a platform using the ARM SMMU (v2), I notice the following behaviour on v5.3 with Will's iommu patch set merged, kernel lock debugging disabled. With iommu.passthrough=1, three consecutive runs: [ 3] 0.0-10.0 sec 4.51 GBytes 3.87 Gbits/sec [ 3] 0.0-10.0 sec 4.53 GBytes 3.89 Gbits/sec [ 3] 0.0-10.0 sec 4.49 GBytes 3.86 Gbits/sec With iommu.passthrough=0: [ 3] 0.0-10.0 sec 1.77 GBytes 1.52 Gbits/sec [ 3] 0.0-10.0 sec 1.82 GBytes 1.56 Gbits/sec [ 3] 0.0-10.0 sec 1.69 GBytes 1.45 Gbits/sec Running perf record -a -g ... followed by perf report --no-children shows: - 15.72% iperf [kernel.vmlinux] [k] _raw_spin_unlock_irqrestor - _raw_spin_unlock_irqrestore - 8.95% arm_smmu_tlb_sync_context arm_smmu_iotlb_sync - __iommu_dma_unmap + 4.54% iommu_dma_unmap_sg + 4.41% iommu_dma_unmap_page - 2.92% alloc_iova_fast - iommu_dma_alloc_iova.isra.26 + 1.54% iommu_dma_map_sg + 1.38% __iommu_dma_map - 2.64% free_iova_fast iommu_dma_free_iova - __iommu_dma_unmap + 1.35% iommu_dma_unmap_sg + 1.29% iommu_dma_unmap_page which seems to be pointing to the SMMU code as a bottleneck. Will suggests that his iommu changes (in his for-joerg/arm-smmu/updates branch), allows IOMMU driver modifications that may have a beneficial effect. Any thoughts? Thanks. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel