linux-kernel - Re: [PATCH v4 3/5] net: mana: explain irq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aDYOFzQrfDFcti-u@yury>
Date: Tue, 27 May 2025 15:10:15 -0400
From: Yury Norov <yury.norov@...il.com>
To: Shradha Gupta <shradhagupta@...ux.microsoft.com>
Cc: Dexuan Cui <decui@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Konstantin Taranov <kotaranov@...rosoft.com>,
	Simon Horman <horms@...nel.org>, Leon Romanovsky <leon@...nel.org>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	Erni Sri Satya Vennela <ernis@...ux.microsoft.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Michael Kelley <mhklinux@...look.com>, linux-hyperv@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Nipun Gupta <nipun.gupta@....com>, Jason Gunthorpe <jgg@...pe.ca>,
	Jonathan Cameron <Jonathan.Cameron@...ei.com>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Kevin Tian <kevin.tian@...el.com>, Long Li <longli@...rosoft.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Rob Herring <robh@...nel.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Wilczy�~Dski <kw@...ux.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>, netdev@...r.kernel.org,
	linux-rdma@...r.kernel.org, Paul Rosswurm <paulros@...rosoft.com>,
	Shradha Gupta <shradhagupta@...rosoft.com>
Subject: Re: [PATCH v4 3/5] net: mana: explain irq_setup() algorithm

So now git will think that you're the author of the patch.

If author and sender are different people, the first line in commit
message body should state that. In this case, it should be:

From: Yury Norov <yury.norov@...il.com>

Please consider this one example

https://patchew.org/linux/20250326-fixed-type-genmasks-v8-0-24afed16ca00@wanadoo.fr/20250326-fixed-type-genmasks-v8-6-24afed16ca00@wanadoo.fr/

Thanks,
Yury

On Tue, May 27, 2025 at 08:58:25AM -0700, Shradha Gupta wrote:
> Commit 91bfe210e196 ("net: mana: add a function to spread IRQs per CPUs")
> added the irq_setup() function that distributes IRQs on CPUs according
> to a tricky heuristic. The corresponding commit message explains the
> heuristic.
> 
> Duplicate it in the source code to make available for readers without
> digging git in history. Also, add more detailed explanation about how
> the heuristics is implemented.
> 
> Signed-off-by: Yury Norov [NVIDIA] <yury.norov@...il.com>
> Signed-off-by: Shradha Gupta <shradhagupta@...ux.microsoft.com>
> ---
>  .../net/ethernet/microsoft/mana/gdma_main.c   | 41 +++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index 4ffaf7588885..f9e8d4d1ba3a 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1288,6 +1288,47 @@ void mana_gd_free_res_map(struct gdma_resource *r)
>  	r->size = 0;
>  }
>  
> +/*
> + * Spread on CPUs with the following heuristics:
> + *
> + * 1. No more than one IRQ per CPU, if possible;
> + * 2. NUMA locality is the second priority;
> + * 3. Sibling dislocality is the last priority.
> + *
> + * Let's consider this topology:
> + *
> + * Node            0               1
> + * Core        0       1       2       3
> + * CPU       0   1   2   3   4   5   6   7
> + *
> + * The most performant IRQ distribution based on the above topology
> + * and heuristics may look like this:
> + *
> + * IRQ     Nodes   Cores   CPUs
> + * 0       1       0       0-1
> + * 1       1       1       2-3
> + * 2       1       0       0-1
> + * 3       1       1       2-3
> + * 4       2       2       4-5
> + * 5       2       3       6-7
> + * 6       2       2       4-5
> + * 7       2       3       6-7
> + *
> + * The heuristics is implemented as follows.
> + *
> + * The outer for_each() loop resets the 'weight' to the actual number
> + * of CPUs in the hop. Then inner for_each() loop decrements it by the
> + * number of sibling groups (cores) while assigning first set of IRQs
> + * to each group. IRQs 0 and 1 above are distributed this way.
> + *
> + * Now, because NUMA locality is more important, we should walk the
> + * same set of siblings and assign 2nd set of IRQs (2 and 3), and it's
> + * implemented by the medium while() loop. We do like this unless the
> + * number of IRQs assigned on this hop will not become equal to number
> + * of CPUs in the hop (weight == 0). Then we switch to the next hop and
> + * do the same thing.
> + */
> +
>  static int irq_setup(unsigned int *irqs, unsigned int len, int node)
>  {
>  	const struct cpumask *next, *prev = cpu_none_mask;
> -- 
> 2.34.1