Mike Dubman <mi...@dev.mellanox.co.il> writes: > we did not get to the bottom for "why". > Tried different mpi packages (mvapich,intel mpi) and the observation hold > true.
Does that mean it's a general effect, unrelated to mxm, or that it is related? > it could be many factors affected by huge heap size (cpu cache misses? > swapness?). I'm sure we're grateful for any information, and I don't mean to be rude, but this could be frustrating to people told they should do performance engineering and trying to understand what might be going on. [Was "heap" a typo?] > On Wed, Sep 30, 2015 at 1:12 PM, Dave Love <d.l...@liverpool.ac.uk> wrote: > >> Mike Dubman <mi...@dev.mellanox.co.il> writes: >> >> > Hello Grigory, >> > >> > We observed ~10% performance degradation with heap size set to unlimited >> > for CFD applications. >> >> OK, but why? It would help to understand what the mechanism is, and why >> MXM specifically tells you to set the stack to the default, which may >> well be wrong for the application.
