netdev - Re: [PATCH net-next 09/15] mlxsw: pci: Use only one event queue

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Message-ID: <20240403123921.GE26556@kernel.org>
Date: Wed, 3 Apr 2024 13:39:21 +0100
From: Simon Horman <horms@...nel.org>
To: Petr Machata <petrm@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, Ido Schimmel <idosch@...dia.com>,
	Amit Cohen <amcohen@...dia.com>, mlxsw@...dia.com
Subject: Re: [PATCH net-next 09/15] mlxsw: pci: Use only one event queue

On Tue, Apr 02, 2024 at 03:54:22PM +0200, Petr Machata wrote:
> From: Amit Cohen <amcohen@...dia.com>
> 
> The device supports two event queues. EQ0 is used for command interface
> completion events. EQ1 is used for completion events of RDQ or SDQ.
> 
> Currently, for each EQE (event queue element), we check the queue number
> and handle accordingly. More than that, for each interrupt we schedule
> tasklets for both EQs. This is really ineffective, especially because of
> the fact that EQ0 is used only as part of driver init/fini, when EMADs are
> not available. There is no point to schedule the tasklet for it and check
> each EQE.
> 
> A previous patch changed the code to poll command interface for each use of
> it. It means that now there is no real reason to use EQ0, as we poll the
> command interface.
> 
> Initialize only one event queue and use it as EQ1 (this is determined by
> queue number). Then, for each interrupt we can schedule the tasklet only
> for one queue and we do not have to check the queue number. This
> simplifies the code and should improve performance. Note that polling
> command interface is ok as we use it only as part of driver init/fini.
> 
> Signed-off-by: Amit Cohen <amcohen@...dia.com>
> Reviewed-by: Ido Schimmel <idosch@...dia.com>
> Signed-off-by: Petr Machata <petrm@...dia.com>

Reviewed-by: Simon Horman <horms@...nel.org>