netdev - Re: [PATCH net-next] eth: mlx5: link NAPI instances to queues and IRQs

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Message-ID: <20240207142529.GA12897@fastly.com>
Date: Wed, 7 Feb 2024 06:25:29 -0800
From: Joe Damato <jdamato@...tly.com>
To: Gal Pressman <gal@...dia.com>
Cc: Tariq Toukan <tariqt@...dia.com>,
	Tariq Toukan <ttoukan.linux@...il.com>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	rrameshbabu@...dia.com, Saeed Mahameed <saeedm@...dia.com>,
	Leon Romanovsky <leon@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"open list:MELLANOX MLX5 core VPI driver" <linux-rdma@...r.kernel.org>
Subject: Re: [PATCH net-next] eth: mlx5: link NAPI instances to queues and
 IRQs

On Wed, Feb 07, 2024 at 08:59:18AM +0200, Gal Pressman wrote:
> On 06/02/2024 21:23, Joe Damato wrote:
> >> The per queue coalesce series is going through internal code review, and is
> >> expected to also be ready in a matter of a few weeks.
> > 
> > OK, great. Thanks for letting me know; we are definitely interested in
> > using this feature.
> 
> Hi Joe,
> Can you please share some details about your usecase for this feature?

It was outlined in the cover letter for the RFC [1].

But, briefly: we set a number of queues (say 16) via ethtool. We then
create a series of n-tuple filters directing certain flows to queues 0-7
via a custom RSS context. The remaining queues, 8-15 are for all other
flows via the default RSS context.

Queues 0-7 are used with busy polling from userland so we want those queues
to have a larger rx/tx-usecs rx/tx-frames than queues 8-15.

We implemented basic support for this in the RFC we sent to the mailing
list.

[1]: https://lore.kernel.org/lkml/20230823223121.58676-1-dev@nalramli.com/