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Message-ID: <1efd1d75-9c5d-4827-3d28-bef044801859@gmail.com>
Date: Thu, 8 Dec 2022 22:22:22 +0200
From: Tariq Toukan <ttoukan.linux@...il.com>
To: Yury Norov <yury.norov@...il.com>, 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>,
haniel 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>,
Tony Luck <tony.luck@...el.com>,
Valentin Schneider <vschneid@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>
Cc: linux-crypto@...r.kernel.org, netdev@...r.kernel.org,
linux-rdma@...r.kernel.org
Subject: Re: [PATCH v3 0/5] cpumask: improve on cpumask_local_spread()
locality
On 12/8/2022 8:30 PM, Yury Norov wrote:
> 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 comparable improvement for its
> users, as in case of mlx5e.
>
> I tested new behavior 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
>
> v1: https://lore.kernel.org/lkml/20221111040027.621646-5-yury.norov@gmail.com/T/
> v2: https://lore.kernel.org/all/20221112190946.728270-3-yury.norov@gmail.com/T/
> v3:
> - fix typo in find_nth_and_andnot_bit();
> - add 5th patch that simplifies cpumask_local_spread();
> - address various coding style nits.
>
> Yury Norov (5):
> 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
> lib/cpumask: reorganize cpumask_local_spread() logic
>
> include/linux/cpumask.h | 20 ++++++++++++++
> include/linux/find.h | 33 +++++++++++++++++++++++
> include/linux/topology.h | 8 ++++++
> kernel/sched/topology.c | 57 ++++++++++++++++++++++++++++++++++++++++
> lib/cpumask.c | 26 +++++-------------
> lib/find_bit.c | 9 +++++++
> 6 files changed, 134 insertions(+), 19 deletions(-)
>
Acked-by: Tariq Toukan <tariqt@...dia.com>
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