9.2 ixgbe tx queue hang

[Jack Vogel]

What he's saying is that the driver should not be using 9K mbuf clusters, I
thought
this had been changed but I see the code in HEAD is still using the larger
clusters
when you up the mtu.  I will put it on my list to change with the next
update to HEAD.


What version of ixgbe are you using?

Jack



On Thu, Mar 20, 2014 at 2:34 PM, Christopher Forgeron
<csforgeron at gmail.com>wrote:

> I have found this:
>
> http://lists.freebsd.org/pipermail/freebsd-net/2013-October/036955.html
>
> I think what you're saying is that;
> - a MTU of 9000 doesn't need to equal a 9k mbuf / jumbo cluster
> - modern NIC drivers can gather 9000 bytes of data from various memory
> locations
> - The fact that I'm seeing 9k jumbo clusters is showing me that my driver
> is trying to allocate 9k of contiguous space, and it's failing.
>
> Please correct me if I'm off here, I'd love to understand more.
>
>
> On Thu, Mar 20, 2014 at 6:13 PM, Garrett Wollman <
> wollman at hergotha.csail.mit.edu> wrote:
>
> > In article
> > <CAB2_NwAOmPtZjB03pdDiTK2OvQgqk-tYf83Jq4Ukt9jnZA8CNA at mail.gmail.com>,
> > csforgeron at gmail.com writes:
> >
> > >50/27433/0 requests for jumbo clusters denied (4k/9k/16k)
> >
> > This is going to screw you.  You need to make sure that no NIC driver
> > ever allocates 9k jumbo pages -- unless you are using one of those
> > mythical drivers that can't do scatter/gather DMA on receive, which
> > you don't appear to be.
> >
> > These failures occur when the driver is trying to replenish its
> > receive queue, but is unable to allocate three *physically* contiguous
> > pages of RAM to construct the 9k jumbo cluster (of which the remaining
> > 3k is simply wasted).  This happens on any moderately active server,
> > once physical memory gets checkerboarded with active single pages,
> > particularly with ZFS where those pages are wired in kernel memory and
> > so can't be evicted.
> >
> > -GAWollman
> >
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