mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-02 14:34:13 -04:00
073cf9e20c
Paolo Abeni says: ==================== udp: reduce cache pressure In the most common use case, many skb fields are not used by recvmsg(), and the few ones actually accessed lays on cold cachelines, which leads to several cache miss per packet. This patch series attempts to reduce such misses with different strategies: * caching the interesting fields in the scratched space * avoid accessing at all uninteresting fields * prefetching Tested using the udp_sink program by Jesper[1] as the receiver, an h/w l4 rx hash on the ingress nic, so that the number of ingress nic rx queues hit by the udp traffic could be controlled via ethtool -L. The udp_sink program was bound to the first idle cpu, to get more stable numbers. On a single numa node receiver: nic rx queues vanilla patched kernel delta 1 1850 kpps 1850 kpps 0% 2 2370 kpps 2700 kpps 13.9% 16 2000 kpps 2220 kpps 11% [1] https://github.com/netoptimizer/network-testing/blob/master/src/udp_sink.c v1 -> v2: - replaced secpath_reset() with skb_release_head_state() - changed udp_dev_scratch fields types to u{32,16} variant, replaced bitfield with bool v2 -> v3: - no changes, tested against apachebench for performances regression ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.