Hi Andrew, > Use a real operating system.
I got a real OS not a virtual one, or what do you mean? Jörg > > On 28 April 2013 09:36, Jörg Saßmannshausen <[email protected]> wrote: > > Hi Josh, > > > > interesting. However, I am not using XEN on that machine at all and I > > don't have the XEN kernel installed. Thus, that is not the problem. > > > > All the best from a sunny London > > > > Jörg > > > > On Sonntag 28 April 2013 Josh Catana wrote: > >> I noticed on systems running xen-kernel netback driver for > >> virtualization, bandwidth drops to very low rates. > >> > >> On Apr 27, 2013 6:19 PM, "Brice Goglin" <[email protected]> wrote: > >> > Hello, > >> > > >> > These cards are QDR and even FDR, you should get 56Gbit/s (we see > >> > about 50Gbit/s in benchmarks iirc). That what I get on sandy-bridge > >> > servers with the exact same IB card model. > >> > > >> > $ ibv_devinfo -v > >> > [...] > >> > > >> > active_width: 4X (2) > >> > active_speed: 14.0 Gbps (16) > >> > > >> > These nodes have been running Debian testing/wheezy (default kernel > >> > and IB packages) for 9 months without problems. > >> > > >> > I had to fix the cables to get 56Gbit/s link state. Without Mellanox > >> > FDR cables, I was only getting 40. So maybe check your cables. And if > >> > you're not 100% sure about your switch, try connecting the nodes > >> > back-to-back. > >> > > >> > You can try upgrading the IB card firmware too. Mine is 2.10.700 > >> > (likely not uptodate anymore, but at least this one works fine). > >> > > >> > Where does your "8.5Gbit/s" come from? IB status or benchmarks? If > >> > benchmarks, it could be related to the PCIe link speed. Upgrading the > >> > BIOS and IB firmware help me too (some reboot gave PCIe Gen1 instead > >> > of Gen3). Here's what you should see in lspci if you get PCIe Gen3 8x > >> > as expected: > >> > > >> > $ sudo lspci -d 15b3: -vv > >> > [...] > >> > > >> > LnkSta: Speed 8GT/s, Width x8 > >> > > >> > Brice > >> > > >> > Le 27/04/2013 22:05, Jörg Saßmannshausen a écrit : > >> > > Dear all, > >> > > > >> > > I was wondering whether somebody has/had similar problems as I have. > >> > > > >> > > We have recenctly purchased a bunch of new nodes. These are > >> > > Sandybridge > >> > > >> > ones > >> > > >> > > with Mellanox ConnectX-3 MT27500 InfiniBand connectors and this is > >> > > where > >> > > >> > I got > >> > > >> > > problems with. > >> > > > >> > > I am usually using Debian Squeeze for my clusters (kernel > >> > > >> > 2.6.32-5-amd64). > >> > > >> > > Unfortunately, as it turned out I cannot use that kernel as my Intel > >> > > NIC > >> > > >> > is > >> > > >> > > not supported here. So I upgraded to 3.2.0-0.bpo.2-amd64 (backport > >> > > >> > kernel to > >> > > >> > > sqeeze). Here I got network but the InfiniBand is not working. The > >> > > >> > device is > >> > > >> > > not even recognized by ibstatus. Thus, I decided to do an upgrade > >> > > (not > >> > > >> > dist- > >> > > >> > > upgrade) to wheezy to get the newer OFED stack. > >> > > > >> > > Here I get the InfiniBand working but only with 8.5 Gb/sec. A simple > >> > > >> > reseating > >> > > >> > > of the plug increases that to 20 Gb/sec (4X DDR), which is still > >> > > slower > >> > > >> > than > >> > > >> > > the speed of the older nodes (40 Gb/sec (4X QDR)). > >> > > > >> > > So I upgraded completely to wheezy (dist-upgrade now) but the > >> > > problem > >> > > >> > does not > >> > > >> > > vanish. > >> > > I re-installed squeeze again and installed a vanilla kernel (3.8.8) > >> > > and > >> > > >> > the > >> > > >> > > latest OFED stack from their site. And guess what: same experiences > >> > > here: After a reboot the IfniniBand speed is 8.5 and reseating the > >> > > plug > >> > > >> > increases > >> > > >> > > that to 20 Gb/sec. It does not matter whether I connect to the edge > >> > > >> > switch or > >> > > >> > > to the main switch, in both cases I got the same > >> > > >> > experiences/observations. > >> > > >> > > Frankly, I am out of ideas now. I don't think the observed speed > >> > > change > >> > > >> > after > >> > > >> > > reseating the plug should happen. I am in touch with the technical > >> > > >> > support > >> > > >> > > here as well but I think we both are a bit confused. > >> > > > >> > > Now, am I right to assume that the Mellanox ConnectX-3 MT27500 are > >> > > QDR > >> > > >> > cards > >> > > >> > > so I should get 40 Gb/sec and not 20 Gb/sec? > >> > > > >> > > Has anybody made similar experiences? Any ideas? > >> > > > >> > > All the best from London > >> > > > >> > > Jörg > >> > > >> > _______________________________________________ > >> > Beowulf mailing list, [email protected] sponsored by Penguin > >> > Computing To change your subscription (digest mode or unsubscribe) > >> > visit http://www.beowulf.org/mailman/listinfo/beowulf > > > > -- > > ************************************************************* > > Jörg Saßmannshausen > > University College London > > Department of Chemistry > > Gordon Street > > London > > WC1H 0AJ > > > > email: [email protected] > > web: http://sassy.formativ.net > > > > Please avoid sending me Word or PowerPoint attachments. > > See http://www.gnu.org/philosophy/no-word-attachments.html > > > > _______________________________________________ > > Beowulf mailing list, [email protected] sponsored by Penguin Computing > > To change your subscription (digest mode or unsubscribe) visit > > http://www.beowulf.org/mailman/listinfo/beowulf -- ************************************************************* Jörg Saßmannshausen University College London Department of Chemistry Gordon Street London WC1H 0AJ email: [email protected] web: http://sassy.formativ.net Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
