[ewg] maximum size of ibv_post_send

[Dotan Barak]

Hi.

Matthew Small wrote:
> Does anyone know what is the maximum size of a transfer using the 
> verbs library?  I have a program which sends increasing amounts of 
> data using ibv_post_send and it seems to be having trouble when I try 
> and send > ~2MB.  Obviously, I can split this up into several 
> communications, but I am unaware if there is a limit (or is it only 
> limited by the amount of memory you can register?).
You can send using InfiniBand up to 2 GB in a message (WR).
Every IB port has an attribute: max_msg_sz which define the maximum 
message size that it supports.

The mentioned value can be limited by the amount of physical memory in 
your host and by the amount of memory that your process
can register.


Dotan