On 10/11/2016 2:50 PM, Doug Ledford wrote: > On 10/11/2016 2:30 PM, Jason Gunthorpe wrote: >> On Tue, Oct 11, 2016 at 02:17:51PM -0400, Doug Ledford wrote: >> >>> Well, not exactly. Even if we put 65520 into the scripts, the kernel >>> will silently drop it down to 65504. It actually won't require anyone >>> change anything, they just won't get the full value. I experimented >>> with this in the past for other reasons and an overly large MTU setting >>> just resulted in the max MTU. I don't know if that's changed, but if it >>> still works that way, this is much less of an issue than it might >>> otherwise be. >> >> So it is just docs and relying on PMTU? That is not as bad.. >> >> Still would be nice to avoid if at all possible.. > > I agree, but we have a test getting ready to commence. We'll know > shortly how much the reduced MTU effects things because they aren't > going to alter any of their setup, just put the new kernel in place, and > see what happens. > >
Long story short on the MTU stuff, the setups whined a bit about not
being able to set the desired MTU, used the new max MTU instead, and
things otherwise worked fine. But, Paolo submitted a v2 patch that
removes this change, so it's all moot anyway.
--
Doug Ledford <dledf...@redhat.com>
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