RFC: How to fix the NFS/iSCSI vs TSO problem

[Christopher Forgeron]

I'm quite sure the problem is on 9.2-RELEASE, not 9.1-RELEASE or earlier,
as a 9.2-STABLE from last year I have doesn't exhibit the problem.  New
code in if.c at line 660 looks to be what is starting this, which makes me
wonder how TSO was being handled before 9.2.

I also like Rick's NFS patch for cluster size. I notice an improvement, but
don't have solid numbers yet. I'm still stress testing it as we speak.


On Wed, Mar 26, 2014 at 11:44 PM, Marcelo Araujo <araujobsdport at gmail.com>wrote:

> Hello All,
>
>
> 2014-03-27 8:27 GMT+08:00 Rick Macklem <rmacklem at uoguelph.ca>:
> >
> > Well, bumping it from 32->35 is all it would take for NFS (can't comment
> > w.r.t. iSCSI). ixgbe uses 100 for the 82598 chip and 32 for the 82599
> > (just so others aren't confused by the above comment). I understand
> > your point was w.r.t. using 100 without blowing the kernel stack, but
> > since the testers have been using "ix" with the 82599 chip which is
> > limited to 32 transmit segments...
> >
> > However, please increase any you know can be safely done from 32->35,
> rick
> >
> >
> I have plenty of machines using Intel X540 that is based on 82599 chipset.
> I have applied Rick's patch on ixgbe to check if the packet size is bigger
> than 65535 or cluster is bigger than 32. So far till now, on FreeBSD
> 9.1-RELEASE this problem does not happens.
>
> Unfortunately all my environment here is based on 9.1-RELEASE, with some
> merges from 10-RELEASE such like: NFS and IXGBE.
>
> Also I have applied the patch that Rick sent in another email with the
> subject 'NFS patch to use pagesize mbuf clusters'. And we can see some
> performance boost over 10Gbps Intel. However here at the company, we are
> still doing benchmarks. If someone wants to have my benchmark result, I can
> send it later.
>
> I'm wondering, if this update on ixgbe from 32->35 could be applied also
> for versions < 9.2. I'm thinking, that this problem arise only on 9-STABLE
> and consequently on 9.2-RELEASE. And fortunately or not 9.1-RELEASE doesn't
> share it.
>
> Best Regards,
> --
> Marcelo Araujo
> araujo at FreeBSD.org
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