[openib-general] Re: [PATCH 1/2] mthca support for max_map_per_fmr device attribute

[Or Gerlitz]

Roland Dreier wrote:
>     Or> Also, if the patch makes sense and the memfree issue is
>     Or> resolved, i'd like to change the name of the device attribute
>     Or> from max_map_per_fmr to max_remaps_per_fmr, i can resend this
>     Or> patch series with this fix.
> 
> The patch makes sense, although of course you need to make sure you
> understand and handle the mem-free case as well if you want it
> applied.  

+ /* FMR can be remapped 2^B - 1 times where B < 32 is the number of
+ *  bits which are not used for MPT addressing */
+ max_map_per_fmr = (1 << (32 - long_log2(mdev->limits.num_mpts))) - 1;

OK, fair enough, i will need at least some kickoff helping... can you 
comment if the above calculation is indeed broken under memfree? if yes, 
is it broken under both Arbel/Sinai? where should i look into the driver 
or i should look in the PRM?

 > I'm not sure changing to max_remaps_per_fmr is really
 > clearer, since the value counts the first mapping of the FMR (which is
 > not a remapping).  But I guess I could be convinced if more people
 > think it's clearer.

remaps means all the maps except the first one, for this stands the "-1" 
in the calculation above. Let me know what makes sense more to you (or 
others if they choose to respond) calling it max_maps_per_fmr (which 
counts also the first map) or calling it max_remaps_per_fmr (so it does 
not count the first map).

Or.