netdev - Re: [net-next 08/15] net/mlx5e: Add hairpin debugfs files

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Message-ID: <20230117104851.2c722c6e@kernel.org>
Date:   Tue, 17 Jan 2023 10:48:51 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Gal Pressman <gal@...dia.com>
Cc:     Saeed Mahameed <saeed@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org,
        Tariq Toukan <tariqt@...dia.com>
Subject: Re: [net-next 08/15] net/mlx5e: Add hairpin debugfs files

On Sun, 15 Jan 2023 12:04:58 +0200 Gal Pressman wrote:
> The hairpin queues are different than other queues in the driver as they
> are controlled by the device (refill, completion handling, etc.).
> Hardware configuration can make a difference in performance when working
> with hairpin, things that wouldn't necessarily affect regular queues the
> driver uses. The debugging process is also more difficult as the driver
> has little control/visibility over these.
> 
> At the end of the day, the debug process *is* going to be playing with
> the queue size/number, this allows us to potentially find a number that
> releases the bottleneck and see how it affects other stages in the pipe.
> Since these cases are unlikely to happen, and changing of these
> parameters can affect the device in other ways, we don't want people to
> just increase them when they encounter performance issues, especially
> not in production environments.
> 
> Does that make sense?

Okay, I think my guess that "debug" here means "wobble it to see if 
the device can go faster" was indeed correct. Long term maybe we should
find a better word for that than "debug".