Date: Mon, 24 Mar 2014 18:29:05 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: Julian Elischer <julian@freebsd.org> Cc: FreeBSD Net <freebsd-net@freebsd.org>, Christopher Forgeron <csforgeron@gmail.com>, Garrett Wollman <wollman@freebsd.org>, Jack Vogel <jfvogel@gmail.com>, Markus Gebert <markus.gebert@hostpoint.ch> Subject: Re: 9.2 ixgbe tx queue hang Message-ID: <349646395.2447442.1395700145224.JavaMail.root@uoguelph.ca> In-Reply-To: <5330632E.3050505@freebsd.org>
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Julian Elischer wrote:
> On 3/23/14, 4:57 PM, Rick Macklem wrote:
> > Christopher Forgeron wrote:
> >>
> >>
> >>
> >>
> >>
> >> On Sat, Mar 22, 2014 at 6:41 PM, Rick Macklem <
> >> rmacklem@uoguelph.ca
> >>> wrote:
> >>
> >>
> >> Christopher Forgeron wrote:
> >>> #if defined(INET) || defined(INET6)
> >>> /* Initialize to max value. */
> >>> if (ifp->if_hw_tsomax == 0)
> >>> ifp->if_hw_tsomax = IP_MAXPACKET;
> >>> KASSERT(ifp->if_hw_tsomax <= IP_MAXPACKET &&
> >>> ifp->if_hw_tsomax >= IP_MAXPACKET / 8,
> >>> ("%s: tsomax outside of range", __func__));
> >>> #endif
> >>>
> >>>
> >>> Should this be the location where it's being set rather than in
> >>> ixgbe? I would assume that other drivers could fall prey to this
> >>> issue.
> >>>
> >> All of this should be prepended with "I'm an NFS guy, not a
> >> networking
> >> guy, so I might be wrong".
> >>
> >> Other drivers (and ixgbe for the 82598 chip) can handle a packet
> >> that
> >> is in more than 32 mbufs. (I think the 82598 handles 100, grep for
> >> SCATTER
> >> in *.h in sys/dev/ixgbe.)
> >>
>
> the Xen backend can not handle mor ethan 32 segments in some versions
> of Xen.
>
Oops, poorly worded. I should have said "Some other drivers...". Yes,
there are several (I once did a find/grep, but didn't keep the output)
that have this 32 limit.
Also, I have no idea if the limit can easily be increased to 35 for them?
(Bryan was able to do that for the virtio network driver.)
rick
ps: If it was just "ix" I wouldn't care as much about this.
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