[Lustre-discuss] Infiniband hot spot avoidance with LMC>0

[Isaac Huang]

On Mon, Apr 27, 2009 at 12:21:41PM -0600, Nathan Dauchy wrote:
> Greetings,
> 
> Does Lustre's o2ib LND take advantage of Infiniband's LID Mask Count
> (LMC) capability?  Might it be included in the future?  I'm looking for
> something similar to the "MV2_USE_HSAM=1" option for Hot-Spot Avoidance
> with MVAPICH2.

Nothing like this exists so far in the o2iblnd. Currently between any
two ports there's only one QP which uses the LIDs as returned by the
SM.

The MVAPICH2 seems to be striping outgoing data over multiple paths
and adjusting path weights dynamically based on perceived speed of the
paths. We'd be interested to take a look if there's a high-level
description of the mechanism.

Thanks,
Isaac