[Beowulf] log_mtts_per_seg in mlx4 driver

Ryan Novosielski novosirj at rutgers.edu
Tue Jul 9 13:12:53 PDT 2019

Hi all,

There seems to be a whole lot of misinformation out there about the appropriate setting for the log_mtts_per_seg parameter in the mlx4 driver. Some folks suggest that it’s different between the RHEL/kernel.org provided driver and Mellanox OFED, some suggest it’s been fixed such that the default can assign 2x the total memory on a node since at least RHEL6.6 (and so one would assume even longer ago in OFED), and some places seem to still be carrying it forward because “maybe it matters.” 

Is anyone here sure of the current state? I’ll probably read the source code if not, but I’d like to spare myself the hassle.

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