From: Peter Zijlstra <peterz@infradead.org>
To: Tariq Toukan <ttoukan.linux@gmail.com>
Cc: Tariq Toukan <tariqt@nvidia.com>,
"David S. Miller" <davem@davemloft.net>,
Saeed Mahameed <saeedm@nvidia.com>,
Jakub Kicinski <kuba@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, Gal Pressman <gal@nvidia.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next V2 2/2] net/mlx5e: Improve remote NUMA preferences used for the IRQ affinity hints
Date: Mon, 18 Jul 2022 23:24:57 +0200 [thread overview]
Message-ID: <YtXPqTM2fH+MUKH7@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <2fc99d26-f804-ad34-1fd7-90cfb123b426@gmail.com>
On Mon, Jul 18, 2022 at 10:49:21PM +0300, Tariq Toukan wrote:
> > > + first = cpumask_local_spread(0, dev->priv.numa_node);
> >
> > Arguably you want something like:
> >
> > first = cpumask_any(cpumask_of_node(dev->priv.numa_node));
>
> Any doesn't sound like what I'm looking for, I'm looking for first.
> I do care about the order within the node, so it's more like
> cpumask_first(cpumask_of_node(dev->priv.numa_node));
>
> Do you think this has any advantage over cpumask_local_spread, if used only
> during the setup phase of the driver?
Only for the poor sod trying to read this code ;-) That is, I had no
idea what cpumask_local_spread() does, while cpumask_first() is fairly
obvious.
> > > @@ -830,8 +887,7 @@ static int comp_irqs_request(struct mlx5_core_dev *dev)
> > > ret = -ENOMEM;
> > > goto free_irqs;
> > > }
> > > - for (i = 0; i < ncomp_eqs; i++)
> > > - cpus[i] = cpumask_local_spread(i, dev->priv.numa_node);
> > > + mlx5_set_eqs_cpus(dev, cpus, ncomp_eqs);
> >
> > So you change this for mlx5, what about the other users of
> > cpumask_local_spread() ?
>
> I took a look at the different netdev users.
> While some users have similar use case to ours (affinity hints), many others
> use cpumask_local_spread in other flows (XPS setting, ring allocations,
> etc..).
>
> Moving them to use the newly exposed API needs some deeper dive into their
> code, especially due to the possible undesired side-effects.
>
> I prefer not to include these changes in my series for now, but probably
> contribute it in a followup work.
Fair enough.
next prev parent reply other threads:[~2022-07-18 21:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-18 12:43 [PATCH net-next V2 0/2] mlx5: Use NUMA distance metrics Tariq Toukan
2022-07-18 12:43 ` [PATCH net-next V2 1/2] sched/topology: Expose sched_numa_find_closest Tariq Toukan
2022-07-18 13:47 ` Peter Zijlstra
2022-07-18 12:43 ` [PATCH net-next V2 2/2] net/mlx5e: Improve remote NUMA preferences used for the IRQ affinity hints Tariq Toukan
2022-07-18 13:50 ` Peter Zijlstra
2022-07-18 19:49 ` Tariq Toukan
2022-07-18 21:24 ` Peter Zijlstra [this message]
2022-07-18 21:57 ` Jakub Kicinski
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