netdev - Re: [PATCH net v2] gve: Cache link

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Date:   Wed, 22 Mar 2023 17:03:56 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     joshwash@...gle.com
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org
Subject: Re: [PATCH net v2] gve: Cache link_speed value from device

On Tue, Mar 21, 2023 at 10:23:32AM -0700, joshwash@...gle.com wrote:
> From: Joshua Washington <joshwash@...gle.com>
> 
> The link speed is never changed for the uptime of a VM, and the current
> implementation sends an admin queue command for each call. Admin queue
> command invocations have nontrivial overhead (e.g., VM exits), which can
> be disruptive to users if triggered frequently. Our telemetry data shows
> that there are VMs that make frequent calls to this admin queue command.
> Caching the result of the original admin queue command would eliminate
> the need to send multiple admin queue commands on subsequent calls to
> retrieve link speed.
> 
> Fixes: 7e074d5a76ca ("gve: Enable Link Speed Reporting in the driver.")
> Signed-off-by: Joshua Washington <joshwash@...gle.com>

Reviewed-by: Simon Horman <simon.horman@...igine.com>