netdev - Re: [PATCH net] xen-netback: fix abuse of napi budget

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Message-ID: <20131210103736.GJ32155@zion.uk.xensource.com>
Date:	Tue, 10 Dec 2013 10:37:36 +0000
From:	Wei Liu <wei.liu2@...rix.com>
To:	David Vrabel <david.vrabel@...rix.com>
CC:	Ian Campbell <Ian.Campbell@...rix.com>,
	Paul Durrant <paul.durrant@...rix.com>,
	<xen-devel@...ts.xen.org>, <netdev@...r.kernel.org>,
	Wei Liu <wei.liu2@...rix.com>
Subject: Re: [PATCH net] xen-netback: fix abuse of napi budget

On Tue, Dec 10, 2013 at 10:30:13AM +0000, David Vrabel wrote:
> On 10/12/13 10:25, Ian Campbell wrote:
> > On Tue, 2013-12-10 at 10:16 +0000, Paul Durrant wrote:
> >> netback seemed to be somewhat confused about the napi budget parameter and
> >> basically ignored it. This patch fixes that, properly limiting the work done
> >> in each poll.
> > 
> > What do you mean "ignored", xenvif_tx_submit seems to be tracking and
> > testing work_done against the budget.
> 
> I have seen this warning in net_rx_action() trigger.
> 
> 	WARN_ON_ONCE(work > weight);
> 
> Which means netback wasn't limiting the work done.
> 

But in the original code work_done is returned by xenvif_tx_submit which
has guard against that situation, right?

Wei.

> David
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