netdev - Re: [PATCH 2.6.30-rc4] r8169: avoid losing MSI interrupts

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Message-Id: <1243205746.3609.2.camel@obelisk.thedillows.org>
Date:	Sun, 24 May 2009 18:55:46 -0400
From:	David Dillow <dave@...dillows.org>
To:	Francois Romieu <romieu@...zoreil.com>
Cc:	Michael Riepe <michael.riepe@...glemail.com>,
	Michael Buesch <mb@...sch.de>,
	Rui Santos <rsantos@...popie.com>,
	Michael Büker <m.bueker@...lin.de>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2.6.30-rc4] r8169: avoid losing MSI interrupts

On Sun, 2009-05-24 at 23:15 +0200, Francois Romieu wrote:
> David Dillow <dave@...dillows.org> :
> [...]
> > This fixes the lockups I've seen. Both MSI and level-triggered interrupt
> > configurations survive over an hour of testing when it would lockup in
> > under 90 seconds before. I am certain of the analysis of the root cause,
> > but there may be better ways to fix it. There may also be a theoretical
> > race window between the ending of a NAPI poll cycle and a link change
> > interrupt coming in, but I'm not sure it would matter. 
> 
> It makes sense.
> 
> If I understand correctly, one should expect to find some pending Tx
> event in the ISR of a failed card when reading the registers with
> ethtool.
> 
> Has someone noticed it ?

Yes, that's part of how I came to this conclusion, I put a debug patch
together that looked at the IRQ status 2 seconds after the last IRQ came
in. Then I waited for the chip to lock and the timer to fire. It showed
0x0085 in the IntrStatus register.

I didn't know I could do that with ethtool, but that would've been a
nice way to go, too. :)

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