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Saeed Mahameed says: ==================== mlx5-updates-2023-03-28 Dragos Tatulea says: ==================== net/mlx5e: RX, Drop page_cache and fully use page_pool For page allocation on the rx path, the mlx5e driver has been using an internal page cache in tandem with the page pool. The internal page cache uses a queue for page recycling which has the issue of head of queue blocking. This patch series drops the internal page_cache altogether and uses the page_pool to implement everything that was done by the page_cache before: * Let the page_pool handle dma mapping and unmapping. * Use fragmented pages with fragment counter instead of tracking via page ref. * Enable skb recycling. The patch series has the following effects on the rx path: * Improved performance for the cases when there was low page recycling due to head of queue blocking in the internal page_cache. The test for this was running a single iperf TCP stream to a rx queue which is bound on the same cpu as the application. |-------------+--------+--------+------+---------| | rq type | before | after | unit | diff | |-------------+--------+--------+------+---------| | striding rq | 30.1 | 31.4 | Gbps | 4.14 % | | legacy rq | 30.2 | 33.0 | Gbps | 8.48 % | |-------------+--------+--------+------+---------| * Small XDP performance degradation. The test was is XDP drop program running on a single rx queue with small packets incoming it looks like this: |-------------+----------+----------+------+---------| | rq type | before | after | unit | diff | |-------------+----------+----------+------+---------| | striding rq | 19725449 | 18544617 | pps | -6.37 % | | legacy rq | 19879931 | 18631841 | pps | -6.70 % | |-------------+----------+----------+------+---------| This will be handled in a different patch series by adding support for multi-packet per page. * For other cases the performance is roughly the same. The above numbers were obtained on the following system: 24 core Intel(R) Xeon(R) Platinum 8380 CPU @ 2.30GHz 32 GB RAM ConnectX-7 single port The breakdown on the patch series is the following: * Preparations for introducing the mlx5e_frag_page struct. * Delete the mlx5e_page_cache struct. * Enable dma mapping from page_pool. * Enable skb recycling and fragment counting. * Do deferred release of pages (just before alloc) to ensure better page_pool cache utilization. ==================== * tag 'mlx5-updates-2023-03-28' of git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux: net/mlx5e: RX, Remove unnecessary recycle parameter and page_cache stats net/mlx5e: RX, Break the wqe bulk refill in smaller chunks net/mlx5e: RX, Increase WQE bulk size for legacy rq net/mlx5e: RX, Split off release path for xsk buffers for legacy rq net/mlx5e: RX, Defer page release in legacy rq for better recycling net/mlx5e: RX, Change wqe last_in_page field from bool to bit flags net/mlx5e: RX, Defer page release in striding rq for better recycling net/mlx5e: RX, Rename xdp_xmit_bitmap to a more generic name net/mlx5e: RX, Enable skb page recycling through the page_pool net/mlx5e: RX, Enable dma map and sync from page_pool allocator net/mlx5e: RX, Remove internal page_cache net/mlx5e: RX, Store SHAMPO header pages in array net/mlx5e: RX, Remove alloc unit layout constraint for striding rq net/mlx5e: RX, Remove alloc unit layout constraint for legacy rq net/mlx5e: RX, Remove mlx5e_alloc_unit argument in page allocation ==================== Link: https://lore.kernel.org/r/20230328205623.142075-1-saeed@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
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