NFS on 10G interface terribly slow

[Rick Macklem]

I wrote:
> Gerrit Kuhn wrote:
> > On Fri, 26 Jun 2015 20:42:08 -0400 (EDT) Rick Macklem
> > <rmacklem at uoguelph.ca> wrote about Re: NFS on 10G interface terribly slow:
> > 
> > RM> Btw, can you tell us what Intel chip(s) you're using?
> > 
> > I have
> > 
> > ix0 at pci0:5:0:0: class=0x020000 card=0x00028086 chip=0x15288086 rev=0x01
> > hdr=0x00 vendor     = 'Intel Corporation'
> >     device     = 'Ethernet Controller 10-Gigabit X540-AT2'
> >     class      = network
> >     subclass   = ethernet
> > 
> Yea, I don't know how to decode this either.
I took a look at the driver and, if I read it correctly, most chips (including
all the X540 ones) use IXGBE_82599_SCATTER.

As such, you will be doing lots of m_defrag() calls, but since disabling TSO
didn't help, that doesn't seem to be the bottleneck.

rick

> I was actually interested in
> what chip Scott was using and getting wire speed.
> As noted in the other reply, since disabling TSO didn't help, you probably
> aren't affected by this issue.
> 
> rick
> 
> > RM> For example, from the "ix" driver:
> > RM> #define IXGBE_82598_SCATTER		100
> > RM> #define IXGBE_82599_SCATTER		32
> > 
> > Hm, I cannot find out into which chipset number this translates for my
> > device...
> > 
> > RM> Btw, it appears that the driver in head/current now sets
> > RM> if_hw_tsomaxsegcount, but the driver in stable/10 does not. This means
> > RM> that the 82599 chip will end up doing the m_defrag() calls for 10.x.
> > 
> > So the next step could even be updating to -current...
> > OTOH, I get the same (bad) resulsts, no matter if TSO is enabled or
> > disabled on the interface.
> > 
> > 
> > cu
> >   Gerrit
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