netdev - Re: NAPI on USB network drivers

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Message-Id: <20170125.143226.525018584694503090.davem@davemloft.net>
Date:   Wed, 25 Jan 2017 14:32:26 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     oneukum@...e.com
Cc:     hayeswang@...ltek.com, netdev@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: NAPI on USB network drivers

From: Oliver Neukum <oneukum@...e.com>
Date: Wed, 25 Jan 2017 10:34:41 +0100

> looking at r8152 I noticed that it uses NAPI. I never considered
> this for the generic USB networking code as you cannot disable
> interrupts for USB. Is it still worth it? What are the benefits?

I think it's not a good approach for getting GRO.

Exactly because of the issue you raise, in that USB drivers
cannot stop the URBs from coming in while running their poll
method.