| Message ID | 20240205110426.764393-4-aleksander.lobakin@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | dma: skip calling no-op sync ops when possible | expand |
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 50ccc4f1ef81..4ab9ac13d362 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1707,7 +1707,8 @@ static size_t iommu_dma_opt_mapping_size(void) } static const struct dma_map_ops iommu_dma_ops = { - .flags = DMA_F_PCI_P2PDMA_SUPPORTED, + .flags = DMA_F_PCI_P2PDMA_SUPPORTED | + DMA_F_CAN_SKIP_SYNC, .alloc = iommu_dma_alloc, .free = iommu_dma_free, .alloc_pages = dma_common_alloc_pages,
When IOMMU is on, the actual synchronization happens in the same cases as with the direct DMA. Advertise %DMA_F_CAN_SKIP_SYNC in IOMMU DMA to skip sync ops calls (indirect) for non-SWIOTLB buffers. perf profile before the patch: 18.53% [kernel] [k] gq_rx_skb 14.77% [kernel] [k] napi_reuse_skb 8.95% [kernel] [k] skb_release_data 5.42% [kernel] [k] dev_gro_receive 5.37% [kernel] [k] memcpy <*> 5.26% [kernel] [k] iommu_dma_sync_sg_for_cpu 4.78% [kernel] [k] tcp_gro_receive <*> 4.42% [kernel] [k] iommu_dma_sync_sg_for_device 4.12% [kernel] [k] ipv6_gro_receive 3.65% [kernel] [k] gq_pool_get 3.25% [kernel] [k] skb_gro_receive 2.07% [kernel] [k] napi_gro_frags 1.98% [kernel] [k] tcp6_gro_receive 1.27% [kernel] [k] gq_rx_prep_buffers 1.18% [kernel] [k] gq_rx_napi_handler 0.99% [kernel] [k] csum_partial 0.74% [kernel] [k] csum_ipv6_magic 0.72% [kernel] [k] free_pcp_prepare 0.60% [kernel] [k] __napi_poll 0.58% [kernel] [k] net_rx_action 0.56% [kernel] [k] read_tsc <*> 0.50% [kernel] [k] __x86_indirect_thunk_r11 0.45% [kernel] [k] memset After patch, lines with <*> no longer show up, and overall cpu usage looks much better (~60% instead of ~72%): 25.56% [kernel] [k] gq_rx_skb 9.90% [kernel] [k] napi_reuse_skb 7.39% [kernel] [k] dev_gro_receive 6.78% [kernel] [k] memcpy 6.53% [kernel] [k] skb_release_data 6.39% [kernel] [k] tcp_gro_receive 5.71% [kernel] [k] ipv6_gro_receive 4.35% [kernel] [k] napi_gro_frags 4.34% [kernel] [k] skb_gro_receive 3.50% [kernel] [k] gq_pool_get 3.08% [kernel] [k] gq_rx_napi_handler 2.35% [kernel] [k] tcp6_gro_receive 2.06% [kernel] [k] gq_rx_prep_buffers 1.32% [kernel] [k] csum_partial 0.93% [kernel] [k] csum_ipv6_magic 0.65% [kernel] [k] net_rx_action iavf yields +10% of Mpps on Rx. This also unblocks batched allocations of XSk buffers when IOMMU is active. Co-developed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> --- drivers/iommu/dma-iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)