Re: NIU - Sun Neptune 10g - Transmit timed out reset (2.6.24)

David Dillow
2008-05-10T00:00:29Z

On Sat, 2008-05-10 at 00:48 +0200, Jesper Krogh wrote:
> Rick Jones wrote:
> >> The number of contextswitches seems enourmous.. over 120.000 sometimes.
> >> When transmitting around the same amount of data (4xgigabit bonded with
> >> 802.3ad) 4x110MB/s the amount of contextswitches only reaches 3-4.000. I
> >> have no idea if this has any relevance.
> >>
> >> Should this setup not be able to fill the pipe?
> >
> > Into which slot was the Neptune inserted? (sure will be nice to have
> > Alex Chiang's pci slot id patch in mainline one of these days :)
> >
> > Is that slot x4, x8, x16?
>
> I can find out excactly .. on monday. But shouldn't x4 be enough anyway?
> wikipedia says 250MB/s pr. lane. And no slots is less than x4, so I
> thought that it didn't matter to me.

lspci -vvv on the slot can tell you what has been negotiated. Also, you
can figure the effective PCIe bandwidth using ~200 MB/s as a rule of
thumb, given the various overheads on the bus. So an x4 won't fully load
up a 10Gbps link.

At least, that's what we're seeing in x8 slots using Infiniband cards,
so your mileage may vary.
--
Dave Dillow
National Center for Computational Science
Oak Ridge National Laboratory
(865) 241-6602 office