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Date: Thu, 10 Nov 2022 20:00:23 -0800
From: Yury Norov <yury.norov@...il.com>
To: linux-kernel@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Barry Song <baohua@...nel.org>,
Ben Segall <bsegall@...gle.com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Gal Pressman <gal@...dia.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Heiko Carstens <hca@...ux.ibm.com>,
Ingo Molnar <mingo@...hat.com>,
Jakub Kicinski <kuba@...nel.org>,
Jason Gunthorpe <jgg@...dia.com>,
Jesse Brandeburg <jesse.brandeburg@...el.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Juri Lelli <juri.lelli@...hat.com>,
Leon Romanovsky <leonro@...dia.com>,
Mel Gorman <mgorman@...e.de>,
Peter Zijlstra <peterz@...radead.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Saeed Mahameed <saeedm@...dia.com>,
Steven Rostedt <rostedt@...dmis.org>,
Tariq Toukan <tariqt@...dia.com>,
Tariq Toukan <ttoukan.linux@...il.com>,
Tony Luck <tony.luck@...el.com>,
Valentin Schneider <vschneid@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>
Cc: Yury Norov <yury.norov@...il.com>, linux-crypto@...r.kernel.org,
netdev@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: [PATCH 0/4] cpumask: improve on cpumask_local_spread() locality
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 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 Valentin's 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 Valentin's case.
I tested it on my VM with the following NUMA configuration:
root@...ian:~# 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
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 | 42 ++++++++++++++++++++++++++++++++++++++++
lib/cpumask.c | 12 ++----------
lib/find_bit.c | 9 +++++++++
6 files changed, 114 insertions(+), 10 deletions(-)
--
2.34.1
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