Christoph Paasch
399f030cd6
mlx5e_skb_from_cqe_mpwrq_nonlinear() copies MLX5E_RX_MAX_HEAD (256) bytes from the page-pool to the skb's linear part. Those 256 bytes include part of the payload. When attempting to do GRO in skb_gro_receive, if headlen > data_offset (and skb->head_frag is not set), we end up aggregating packets in the frag_list. This is of course not good when we are CPU-limited. Also causes a worse skb->len/truesize ratio,... So, let's avoid copying parts of the payload to the linear part. We use eth_get_headlen() to parse the headers and compute the length of the protocol headers, which will be used to copy the relevant bits of the skb's linear part. We still allocate MLX5E_RX_MAX_HEAD for the skb so that if the networking stack needs to call pskb_may_pull() later on, we don't need to reallocate memory. This gives a nice throughput increase (ARM Neoverse-V2 with CX-7 NIC and LRO enabled): BEFORE: ======= (netserver pinned to core receiving interrupts) $ netperf -H 10.221.81.118 -T 80,9 -P 0 -l 60 -- -m 256K -M 256K 87380 16384 262144 60.01 32547.82 (netserver pinned to adjacent core receiving interrupts) $ netperf -H 10.221.81.118 -T 80,10 -P 0 -l 60 -- -m 256K -M 256K 87380 16384 262144 60.00 52531.67 AFTER: ====== (netserver pinned to core receiving interrupts) $ netperf -H 10.221.81.118 -T 80,9 -P 0 -l 60 -- -m 256K -M 256K 87380 16384 262144 60.00 52896.06 (netserver pinned to adjacent core receiving interrupts) $ netperf -H 10.221.81.118 -T 80,10 -P 0 -l 60 -- -m 256K -M 256K 87380 16384 262144 60.00 85094.90 Additional tests across a larger range of parameters w/ and w/o LRO, w/ and w/o IPv6-encapsulation, different MTUs (1500, 4096, 9000), different TCP read/write-sizes as well as UDP benchmarks, all have shown equal or better performance with this patch. For XDP pull at most ETH_HLEN bytes in the linear area so that XDP_PASS can also benefit from this improvement and keep things simple when dealing with skb geometry changes from the XDP program. Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Saeed Mahameed <saeedm@nvidia.com> Signed-off-by: Christoph Paasch <cpaasch@openai.com> Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com> Signed-off-by: Tariq Toukan <tariqt@nvidia.com> Link: https://patch.msgid.link/20260601061522.398044-3-tariqt@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! 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