[ofa-general] [PATCH] mlx4: implement MOD_STAT_CFG command to use for changing ConnectX page size

[Jack Morgenstein]

On Monday 19 May 2008 17:49, Roland Dreier wrote:
>  > This is in case at some installation, the administrator wishes to use
>  > the legacy device page size of 12, for example.  Having a module
>  > parameter enables such tweaking to be done painlessly.
> 
> And why would the administrator want that?
> 
I just remembered.  If we create FMRs using 512 as the device page size, we will
use 8 times the MTT entries as we would if the page size was 4K.  The ULP (rds and iser)
can run out of MTT entries much faster.

This can give an administrator a quick workaround if needed (until we fix the
resource allocator to allow bitmaps larger than 2^20 -- which is the current default
max number of MTTs).  (The allocator's problem is that kzalloc cannot allocate a block
larger than 128 KB (= 1Meg bits).

- Jack