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Date: Fri, 6 Feb 2026 20:30:26 -0800
From: Jakub Kicinski <kuba@kernel.org>
To: Daniel Zahka <daniel.zahka@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>, Eric Dumazet
 <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Simon Horman
 <horms@kernel.org>, Donald Hunter <donald.hunter@gmail.com>, Boris Pismenny
 <borisp@nvidia.com>, Saeed Mahameed <saeedm@nvidia.com>, Leon Romanovsky
 <leon@kernel.org>, Tariq Toukan <tariqt@nvidia.com>, Mark Bloch
 <mbloch@nvidia.com>, Andrew Lunn <andrew+netdev@lunn.ch>, Shuah Khan
 <shuah@kernel.org>, Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
 netdev@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH net-next 7/9] mlx5: psp: implement deferred tx key
 deletion
Message-ID: <20260206203026.2bb64661@kernel.org>
In-Reply-To: <20260204-psp-v1-7-5f034e2dfa36@gmail.com>
References: <20260204-psp-v1-0-5f034e2dfa36@gmail.com>
	<20260204-psp-v1-7-5f034e2dfa36@gmail.com>
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On Wed, 04 Feb 2026 07:20:11 -0800 Daniel Zahka wrote:
> Implement the deferred tx key deletion api. In the case of mlx5,
> mlx5e_psp_tx_grace_begin() records the number of wqes retired on each
> tx queue, and then mlx5e_psp_tx_grace_end() returns 0 only if
> all tx queues have advanced a full ring cycle past the point where
> they were snapshotted.

Either Friday night enlightenment or I'm very tired -- but I wonder if
we can do with BQL, without touching the driver at all?

struct dql {
	/* Fields accessed in enqueue path (dql_queued) */
	unsigned int	num_queued;		/* Total ever queued */

...

	/* Fields accessed only by completion path (dql_completed) */
	unsigned int	num_completed;		/* Total ever completed */
...
};

These are free running counters of how many bytes were queued to 
the driver and how many driver finished xmit'ing.