netdev - Re: [PATCH net-next] ibmvnic: Defer tx completion processing using a wait queue

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Message-ID: <1460491940.6473.592.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Tue, 12 Apr 2016 13:12:20 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	John Allen <jallen@...ux.vnet.ibm.com>
Cc:	Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>,
	netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH net-next] ibmvnic: Defer tx completion processing using
 a wait queue

On Tue, 2016-04-12 at 14:38 -0500, John Allen wrote:
> Moves tx completion processing out of interrupt context, deferring work
> using a wait queue. With this work now deferred, we must account for the
> possibility that skbs can be sent faster than we can process completion
> requests in which case the tx buffer will overflow. If the tx buffer is
> full, ibmvnic_xmit will return NETDEV_TX_BUSY and stop the current tx
> queue. Subsequently, the queue will be restarted in ibmvnic_complete_tx
> when all pending tx completion requests have been cleared.

1) Why is this needed ?

2) If it is needed, why is this not done in a generic way, so that other
drivers can use this ?

Thanks.