Re: Maximum size for memory registration (ibv_reg_mr)

Or Gerlitz
2010-10-07T11:21:36Z

Eli Cohen wrote:
> If you create a MR in kernel, it covers the entire address space and
> the HCA does not pose any limit since you do not consume MTTs. And if
> you use MTTs then the page size is a parameter in this calculation -
> huge page, regular page etc.
I agree that the kernel case is not of large interest, even though what
you wrote only applies for dma mr, when some FMR scheme is used, MTTs
are consumed, ofcourse. But, typically, kernel code will not go to the
order of giga-bytes, and in other words will not hit the HCA limit.

> Do leaving it as is seems to be the most accurate thing...
I would implement it for regular pages and drop a note in the libibverbs
man page that if huge pages are used (well, the huge pages patch set
isn't fully merged, maybe its about time to make this happen...) then
the actual limit is bigger, e.g follows the proportion between the
regular to the huge pages used.

Or.