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Some platforms exhibit very high costs with CONFIG_STACKPROTECTOR_STRONG=y when a function needs to pass the address of a local variable to external functions. eth_type_trans() (and its callers) is showing this anomaly on AMD EPYC 7B12 platforms (and maybe others). We could : 1) inline eth_type_trans() This would help if its callers also has the same issue, and the canary cost would be paid by the callers already. This is a bit cumbersome because netdev_uses_dsa() is pulling whole <net/dsa.h> definitions. 2) Compile net/ethernet/eth.c with -fno-stack-protector This would weaken security. 3) Hack eth_type_trans() to temporarily use skb->dev as a place holder if skb_header_pointer() needs to pull 2 bytes not present in skb->head. This patch implements 3), and brings a 5% improvement on TX/RX intensive workload (tcp_rr 10,000 flows) on AMD EPYC 7B12. Removing CONFIG_STACKPROTECTOR_STRONG on this platform can improve performance by 25 %. This means eth_type_trans() issue is not an isolated artifact. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://patch.msgid.link/20251121061725.206675-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.