+2.9% perf: Avoid copying in send core, further batch memory optimisation #818
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Introduce new prepare_packet callback for the initialization of send buffers; contrary to the per-thread initialization callback where this was done previously, prepare_packet can be called multiple times, once for each send buffer. Make use of this to prepare packets to send directly in the batch buffers instead of copying them over.
The ip field was only still used in send-bsd and only on a failure path for logging, which does not seem like a strong justification for keeping it around, especially given that it can always be read from the packet data itself. While removing the ip field, align buf such that the IP header is going to start at a 32 bit aligned address, which again results in 32 bit header field access to be faster because of ideal alignment.
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I broke something, let me come back with this at a later time. |
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ipfield frombatch->packets[]and align the packet data such that the IP headers start at a 32 bit boundary, speeding up 32 bit header field accessThe former results in a ~2% and the latter a further ~0.9% improvement to send rate at 10 GbE on lower-end hardware, while (arguably) improving code structure, or at least not making it worse.
Tested on macOS Sonoma, FreeBSD 14 and Ubuntu 23.10; smoke tested various probe modules.