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09a99ab16c
Affinity hints were being set to CPUs in local NUMA node first, and then in other CPUs. This was creating 2 unintended issues: 1. Channels created to be assigned each to a different physical core were assigned to hyperthreading siblings because of being in same NUMA node. Since the patch previous to this one, this did not longer happen with default rss_cpus modparam because less channels are created. 2. XDP channels could be assigned to CPUs in different NUMA nodes, decreasing performance too much (to less than half in some of my tests). This patch sets the affinity hints spreading the channels only in local NUMA node's CPUs. A fallback for the case that no CPU in local NUMA node is online has been added too. Example of CPUs being assigned in a non optimal way before this and the previous patch (note: in this system, xdp-8 to xdp-15 are created because num_possible_cpus == 64, but num_present_cpus == 32 so they're never used): $ lscpu | grep -i numa NUMA node(s): 2 NUMA node0 CPU(s): 0-7,16-23 NUMA node1 CPU(s): 8-15,24-31 $ grep -H . /proc/irq/*/0000:07:00.0*/../smp_affinity_list /proc/irq/141/0000:07:00.0-0/../smp_affinity_list:0 /proc/irq/142/0000:07:00.0-1/../smp_affinity_list:1 /proc/irq/143/0000:07:00.0-2/../smp_affinity_list:2 /proc/irq/144/0000:07:00.0-3/../smp_affinity_list:3 /proc/irq/145/0000:07:00.0-4/../smp_affinity_list:4 /proc/irq/146/0000:07:00.0-5/../smp_affinity_list:5 /proc/irq/147/0000:07:00.0-6/../smp_affinity_list:6 /proc/irq/148/0000:07:00.0-7/../smp_affinity_list:7 /proc/irq/149/0000:07:00.0-8/../smp_affinity_list:16 /proc/irq/150/0000:07:00.0-9/../smp_affinity_list:17 /proc/irq/151/0000:07:00.0-10/../smp_affinity_list:18 /proc/irq/152/0000:07:00.0-11/../smp_affinity_list:19 /proc/irq/153/0000:07:00.0-12/../smp_affinity_list:20 /proc/irq/154/0000:07:00.0-13/../smp_affinity_list:21 /proc/irq/155/0000:07:00.0-14/../smp_affinity_list:22 /proc/irq/156/0000:07:00.0-15/../smp_affinity_list:23 /proc/irq/157/0000:07:00.0-xdp-0/../smp_affinity_list:8 /proc/irq/158/0000:07:00.0-xdp-1/../smp_affinity_list:9 /proc/irq/159/0000:07:00.0-xdp-2/../smp_affinity_list:10 /proc/irq/160/0000:07:00.0-xdp-3/../smp_affinity_list:11 /proc/irq/161/0000:07:00.0-xdp-4/../smp_affinity_list:12 /proc/irq/162/0000:07:00.0-xdp-5/../smp_affinity_list:13 /proc/irq/163/0000:07:00.0-xdp-6/../smp_affinity_list:14 /proc/irq/164/0000:07:00.0-xdp-7/../smp_affinity_list:15 /proc/irq/165/0000:07:00.0-xdp-8/../smp_affinity_list:24 /proc/irq/166/0000:07:00.0-xdp-9/../smp_affinity_list:25 /proc/irq/167/0000:07:00.0-xdp-10/../smp_affinity_list:26 /proc/irq/168/0000:07:00.0-xdp-11/../smp_affinity_list:27 /proc/irq/169/0000:07:00.0-xdp-12/../smp_affinity_list:28 /proc/irq/170/0000:07:00.0-xdp-13/../smp_affinity_list:29 /proc/irq/171/0000:07:00.0-xdp-14/../smp_affinity_list:30 /proc/irq/172/0000:07:00.0-xdp-15/../smp_affinity_list:31 CPUs assignments after this and previous patch, so normal channels created only one per core in NUMA node and affinities set only to local NUMA node: $ grep -H . /proc/irq/*/0000:07:00.0*/../smp_affinity_list /proc/irq/116/0000:07:00.0-0/../smp_affinity_list:0 /proc/irq/117/0000:07:00.0-1/../smp_affinity_list:1 /proc/irq/118/0000:07:00.0-2/../smp_affinity_list:2 /proc/irq/119/0000:07:00.0-3/../smp_affinity_list:3 /proc/irq/120/0000:07:00.0-4/../smp_affinity_list:4 /proc/irq/121/0000:07:00.0-5/../smp_affinity_list:5 /proc/irq/122/0000:07:00.0-6/../smp_affinity_list:6 /proc/irq/123/0000:07:00.0-7/../smp_affinity_list:7 /proc/irq/124/0000:07:00.0-xdp-0/../smp_affinity_list:16 /proc/irq/125/0000:07:00.0-xdp-1/../smp_affinity_list:17 /proc/irq/126/0000:07:00.0-xdp-2/../smp_affinity_list:18 /proc/irq/127/0000:07:00.0-xdp-3/../smp_affinity_list:19 /proc/irq/128/0000:07:00.0-xdp-4/../smp_affinity_list:20 /proc/irq/129/0000:07:00.0-xdp-5/../smp_affinity_list:21 /proc/irq/130/0000:07:00.0-xdp-6/../smp_affinity_list:22 /proc/irq/131/0000:07:00.0-xdp-7/../smp_affinity_list:23 /proc/irq/132/0000:07:00.0-xdp-8/../smp_affinity_list:0 /proc/irq/133/0000:07:00.0-xdp-9/../smp_affinity_list:1 /proc/irq/134/0000:07:00.0-xdp-10/../smp_affinity_list:2 /proc/irq/135/0000:07:00.0-xdp-11/../smp_affinity_list:3 /proc/irq/136/0000:07:00.0-xdp-12/../smp_affinity_list:4 /proc/irq/137/0000:07:00.0-xdp-13/../smp_affinity_list:5 /proc/irq/138/0000:07:00.0-xdp-14/../smp_affinity_list:6 /proc/irq/139/0000:07:00.0-xdp-15/../smp_affinity_list:7 Signed-off-by: Íñigo Huguet <ihuguet@redhat.com> Acked-by: Martin Habets <habetsm.xilinx@gmail.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
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text 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.