[Users] PortXmitWait?

[Hal Rosenstock]

By the fact that you didn't mention PortXmitDiscards, does it mean that
these are 0 ? Assuming so, PortXmitWait is indicating there is some
congestion but it has not risen to the level of dropping packets. It's the
rate of increase of the XmitWait counter that's important rather than the
absolute number so if you want to chase this, the focus should be on the
ports most congested.

Since the old tool didn't report XmitWait counters, it's hard to know
whether this is the same as before or not unless you did this manually.

Was the routing previously fat tree ? Are there any other fat tree related
log messages in the OpenSM log ? Is there any fat tree configuration of
compute and/or I/O nodes ?

Any idea on what is the traffic pattern ? Are you running MPI ?

-- Hal


On Wed, Mar 12, 2014 at 8:17 PM, Florent Parent <
florent.parent at calculquebec.ca> wrote:

>
> Hello IB users,
>
> We recently migrated our opensm from 3.2.6 to 3.3.17. In this upgrade, we
> moved to CentOS6.5 with the stock RDMA and infiniband-diags_1.5.12-5., and
> running opensm 3.3.17. Routing is FatTree:
> General fabric topology info
> ============================
> - FatTree rank (roots to leaf switches): 3
> - FatTree max switch rank: 2
> - Fabric has 966 CAs, 966 CA ports (603 of them CNs), 186 switches
> - Fabric has 36 switches at rank 0 (roots)
> - Fabric has 64 switches at rank 1
> - Fabric has 86 switches at rank 2 (86 of them leafs)
>
> Now to the question: ibqueryerrors 1.5.12 is reporting high PortXmitWait
> values throughout the fabric. We did not see this counter before (it was
> not reported by the older ibqueryerrors.pl)
>
> To give an idea of the scale of the counters, here's a capture of
> ibqueryerrors --data on one specific I4 switch, 10 seconds after clearing
> the counters (-k -K):
>
> GUID 0x21283a83b30050 port 4:  PortXmitWait == 2932676  PortXmitData ==
> 90419517 (344.923MB)  PortRcvData == 1526963011 (5.688GB)
> GUID 0x21283a83b30050 port 5:  PortXmitWait == 3110105  PortXmitData ==
> 509580912 (1.898GB)  PortRcvData == 13622 (53.211KB)
> GUID 0x21283a83b30050 port 6:  PortXmitWait == 8696397  PortXmitData ==
> 480870802 (1.791GB)  PortRcvData == 17067 (66.668KB)
> GUID 0x21283a83b30050 port 7:  PortXmitWait == 1129568  PortXmitData ==
> 126483825 (482.497MB)  PortRcvData == 24973385 (95.266MB)
> GUID 0x21283a83b30050 port 8:  PortXmitWait == 29021  PortXmitData ==
> 19444902 (74.176MB)  PortRcvData == 84447725 (322.143MB)
> GUID 0x21283a83b30050 port 9:  PortXmitWait == 4945130  PortXmitData ==
> 161911244 (617.642MB)  PortRcvData == 27161 (106.098KB)
> GUID 0x21283a83b30050 port 10:  PortXmitWait == 16795  PortXmitData ==
> 35572510 (135.698MB)  PortRcvData == 681174731 (2.538GB)
> ... (this goes on for every active ports)
>
> We are not observing any failures, so I suspect that I need help to
> interpret these numbers. Do I need to be worried?
>
> Cheers,
> Florent
>
>
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