netdev - Re: [PATCH net-next 5/7] bnxt_en: Change MSIX/NQs allocation policy

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Message-ID: <7f4f5a1f-1320-4082-bfe2-6b1eb422e37b@intel.com>
Date: Tue, 9 Apr 2024 16:40:12 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Michael Chan <michael.chan@...adcom.com>, <davem@...emloft.net>
CC: <netdev@...r.kernel.org>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <pavan.chebbi@...adcom.com>,
	<andrew.gospodarek@...adcom.com>, Vikas Gupta <vikas.gupta@...adcom.com>
Subject: Re: [PATCH net-next 5/7] bnxt_en: Change MSIX/NQs allocation policy



On 4/9/2024 2:54 PM, Michael Chan wrote:
> From: Vikas Gupta <vikas.gupta@...adcom.com>
> 
> The existing scheme sets aside a number of MSIX/NQs for the RoCE
> driver whether the RoCE driver is registered or not.  This scheme
> is not flexible and limits the resources available for the L2 rings
> if RoCE is never used.
> 
> Modify the scheme so that the RoCE MSIX/NQs can be used by the L2
> driver if they are not used for RoCE.  The MSIX/NQs are now
> represented by 3 fields.  bp->ulp_num_msix_want contains the
> desired default value, edev->ulp_num_msix_vec contains the
> available value (but not necessarily in use), and
> ulp_tbl->msix_requested contains the actual value in use by RoCE.
> 
> The L2 driver can dip into edev->ulp_num_msix_vec if necessary.
> 
> We need to add rtnl_lock() back in bnxt_register_dev() and
> bnxt_unregister_dev() to synchronize the MSIX usage between L2 and
> RoCE.
> 
> Reviewed-by: Andy Gospodarek <andrew.gospodarek@...adcom.com>
> Signed-off-by: Vikas Gupta <vikas.gupta@...adcom.com>
> Signed-off-by: Michael Chan <michael.chan@...adcom.com>
> ---

Whats the behavior if the L2 driver dips into this pool and then RoCE is
enabled later?

I guess RoCE would fail to get the resources it needs, but then system
administrator could re-configure the L2 device to use fewer resources?

Makes sense.

Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>

Thanks,
Jake