netdev - Re: [PATCH net 2/2] bnx2x: fix napi poll return value for repoll

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Message-ID: <1421768677.4832.7.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Tue, 20 Jan 2015 07:44:37 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Govindarajulu Varadarajan <_govind@....com>
Cc:	Willem de Bruijn <willemb@...gle.com>, davem@...emloft.net,
	netdev@...r.kernel.org, ariel.elior@...gic.com, ssujith@...co.com,
	benve@...co.com
Subject: Re: [PATCH net 2/2] bnx2x: fix napi poll return value for repoll

On Tue, 2015-01-20 at 20:54 +0530, Govindarajulu Varadarajan wrote:
> On Tue, 20 Jan 2015, Eric Dumazet wrote:
> 
> > On Tue, 2015-01-20 at 18:46 +0530, Govindarajulu Varadarajan wrote:
> >> With the commit d75b1ade567ffab ("net: less interrupt masking in NAPI") napi repoll
> >> is done only when work_done == budget. When in busy_poll is we return 0 in
> >> napi_poll. We should return budget. Also do not return workdone > budget.
> >>
> >
> > I am not sure.
> >
> 
> This is based on f41281d02f8b94e136f78cb1b6a5d78182c222bd &
> 9dfa9a27b620640322588df399eb8f624b48d877
> 
> I do not know about bnx2x, but in enic driver, when busy_poll is enables
> rq clean is not happening. This is because, in napi_poll() when
> work_done < budget, we do not repoll. At this point, enic has disables rq intr
> and has not called napi_complete. Driver assumes that napi will repoll.
> Which does not happen.
> 
> Lot of drivers I have checked return full budget if they want to repoll.
> eg. mlx4_en_poll_rx_cq()

I was referring to the "workdone > budget" condition.

But yes, the fix about busy poll seems needed.



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