[mvapich-discuss] Performance Drop using MVAPICH-0.97-mlx2.1.0

[Pavel Shamis (Pasha)]

Hi,
By default rc4 use MTU size 2K and it is not optimal for this HCA.
In rc5 it will be changed to 1K.
So in rc4 you can use configuration parameter VIADEV_DEFAULT_MTU=1024 
that will fix the issue.

Regards,
Pasha

Alfred Torrez wrote:
> Hi,
> 
> I installed OpenFabrics OFED-1.0-rc4 (with mvapich-0.97-mlx2.1.0) on a 
> few nodes in our cluster.  Using the osu_bw benchmark, I noticed that 
> peak bw performance dropped by about 200MB/sec vs the other nodes that 
> have mvapich-gen2-1.0-105ninstalled.  In fact, this is the lowest 
> performance I have ever seen using various versions of mvapich on this 
> cluster.  IPoIB and verbs level ping-pong performance did not seem to 
> drop so I am wondering if this is related to a tuning parameter that I 
> need to adjust (I played with some of them)?  I did have to upgrade HCA 
> firmware from 3.3.2 to 3.4 due to the "couldn't modify SRQ limit" error.
> 
> Cluster specifics are:
> 
> Xeon 2.2GHz
> FC3 2.6.14.4
> Mellanox MT23108-CE128 HCA fw. ver. 3.4.0
> 
> Thanks,
> 
> Alfred
> 
> 
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