Date: Thu, 20 Jul 2017 10:00:27 -0400
To: Benjamin Poirier <bpoirier@suse.com>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        intel-wired-lan@lists.osuosl.org,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Subject: Re: commit 16ecba59 breaks 82574L under heavy load.
Message-ID: <20170720140027.GR18556@csclub.uwaterloo.ca>
References: <20170718142109.GO18556@csclub.uwaterloo.ca>
 <20170718231435.64us7vu67wtp6pwe@f1.synalogic.ca>
 <20170719141953.GQ18556@csclub.uwaterloo.ca>
 <20170720000747.4jiadqubv7hg5esz@f1.synalogic.ca>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170720000747.4jiadqubv7hg5esz@f1.synalogic.ca>
User-Agent: Mutt/1.5.23 (2014-03-12)
From: lsorense@csclub.uwaterloo.ca (Lennart Sorensen)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 871
Lines: 24

On Wed, Jul 19, 2017 at 05:07:47PM -0700, Benjamin Poirier wrote:
> Are you sure about this? In my testing, while triggering the overrun
> with the msleep, I read ICR when entering e1000_msix_other() and RXO is
> consistently set.

I had thousands of calls to e1000_msix_other where the only bit set
was OTHER.

I don't know if the cause is overruns, it just seems plausible.

> I'm working on a patch that uses that fact to handle the situation and
> limit the interrupt.

Excellent.

Running in MSI mode rather than MSI-X seems to not have the problem of
unexpected interrupts, but has other issues (such as loosing the IRQ
affinity setting if you do ifconfig down;ifconfig up on the interface,
which does not happen in MSI-X's case.)  That's rather annoying as you
can't set the affinity before bringing up the interface which is rather
undesirable.

-- 
Len Sorensen