* [LibreQoS] Fwd: [PATCH v2 0/4] cpumask: improve on cpumask_local_spread() locality
[not found] <20221112190946.728270-1-yury.norov@gmail.com>
@ 2022-11-28 8:11 ` Dave Taht
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From: Dave Taht @ 2022-11-28 8:11 UTC (permalink / raw)
To: libreqos
---------- Forwarded message ---------
From: Yury Norov <yury.norov@gmail.com>
Date: Sat, Nov 12, 2022 at 11:14 AM
Subject: [PATCH v2 0/4] cpumask: improve on cpumask_local_spread() locality
To: <linux-kernel@vger.kernel.org>, David S. Miller
<davem@davemloft.net>, Andy Shevchenko
<andriy.shevchenko@linux.intel.com>, Barry Song <baohua@kernel.org>,
Ben Segall <bsegall@google.com>, haniel Bristot de Oliveira
<bristot@redhat.com>, Dietmar Eggemann <dietmar.eggemann@arm.com>, Gal
Pressman <gal@nvidia.com>, Greg Kroah-Hartman
<gregkh@linuxfoundation.org>, Heiko Carstens <hca@linux.ibm.com>, Ingo
Molnar <mingo@redhat.com>, Jakub Kicinski <kuba@kernel.org>, Jason
Gunthorpe <jgg@nvidia.com>, Jesse Brandeburg
<jesse.brandeburg@intel.com>, Jonathan Cameron
<Jonathan.Cameron@huawei.com>, Juri Lelli <juri.lelli@redhat.com>,
Leon Romanovsky <leonro@nvidia.com>, Mel Gorman <mgorman@suse.de>,
Peter Zijlstra <peterz@infradead.org>, Rasmus Villemoes
<linux@rasmusvillemoes.dk>, Saeed Mahameed <saeedm@nvidia.com>, Steven
Rostedt <rostedt@goodmis.org>, Tariq Toukan <tariqt@nvidia.com>, Tariq
Toukan <ttoukan.linux@gmail.com>, Tony Luck <tony.luck@intel.com>,
Valentin Schneider <vschneid@redhat.com>, Vincent Guittot
<vincent.guittot@linaro.org>
Cc: Yury Norov <yury.norov@gmail.com>, <linux-crypto@vger.kernel.org>,
<netdev@vger.kernel.org>, <linux-rdma@vger.kernel.org>
cpumask_local_spread() currently checks local node for presence of i'th
CPU, and then if it finds nothing makes a flat search among all non-local
CPUs. We can do it better by checking CPUs per NUMA hops.
This series is inspired by Tariq Toukan and Valentin Schneider's "net/mlx5e:
Improve remote NUMA preferences used for the IRQ affinity hints"
https://patchwork.kernel.org/project/netdevbpf/patch/20220728191203.4055-3-tariqt@nvidia.com/
According to their measurements, for mlx5e:
Bottleneck in RX side is released, reached linerate (~1.8x speedup).
~30% less cpu util on TX.
This patch makes cpumask_local_spread() traversing CPUs based on NUMA
distance, just as well, and I expect comparabale improvement for its
users, as in case of mlx5e.
I tested new behavior on my VM with the following NUMA configuration:
root@debian:~# numactl -H
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3
node 0 size: 3869 MB
node 0 free: 3740 MB
node 1 cpus: 4 5
node 1 size: 1969 MB
node 1 free: 1937 MB
node 2 cpus: 6 7
node 2 size: 1967 MB
node 2 free: 1873 MB
node 3 cpus: 8 9 10 11 12 13 14 15
node 3 size: 7842 MB
node 3 free: 7723 MB
node distances:
node 0 1 2 3
0: 10 50 30 70
1: 50 10 70 30
2: 30 70 10 50
3: 70 30 50 10
And the cpumask_local_spread() for each node and offset traversing looks
like this:
node 0: 0 1 2 3 6 7 4 5 8 9 10 11 12 13 14 15
node 1: 4 5 8 9 10 11 12 13 14 15 0 1 2 3 6 7
node 2: 6 7 0 1 2 3 8 9 10 11 12 13 14 15 4 5
node 3: 8 9 10 11 12 13 14 15 4 5 6 7 0 1 2 3
v1: https://lore.kernel.org/lkml/20221111040027.621646-5-yury.norov@gmail.com/T/
v2:
- use bsearch() in sched_numa_find_nth_cpu();
- fix missing 'static inline' in 3rd patch.
Yury Norov (4):
lib/find: introduce find_nth_and_andnot_bit
cpumask: introduce cpumask_nth_and_andnot
sched: add sched_numa_find_nth_cpu()
cpumask: improve on cpumask_local_spread() locality
include/linux/cpumask.h | 20 +++++++++++++++
include/linux/find.h | 33 ++++++++++++++++++++++++
include/linux/topology.h | 8 ++++++
kernel/sched/topology.c | 55 ++++++++++++++++++++++++++++++++++++++++
lib/cpumask.c | 12 ++-------
lib/find_bit.c | 9 +++++++
6 files changed, 127 insertions(+), 10 deletions(-)
--
2.34.1
--
This song goes out to all the folk that thought Stadia would work:
https://www.linkedin.com/posts/dtaht_the-mushroom-song-activity-6981366665607352320-FXtz
Dave Täht CEO, TekLibre, LLC
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