[rds-devel] RDS IB transport software flow control?

[Or Gerlitz]

Olaf Kirch wrote:
> On Monday 05 November 2007 08:33, Or Gerlitz wrote:
>> Zach, Rick,
>>
>>  From the patch below I conclude that the RDS IB transport relies on IB 
>> RNR NAKs, is this correct? if yes, why?
> 
> Yes, it does rely on RNRs. As to the why - I don't know enough of the
> history behind the design decisions of RDS. But I assume the point
> was that this would be simpler than a credit based system. Whether that 
> is actually true is an open question though - RDS can be quite memory
> hungry, if you let it run unchecked; and once you do run into a congestion
> scenario, things will actually get quite slow, as congestion updates
> involve sending the entire 8K congestion map down all RCs.

Can you shed some more light on this congestion map design / 
implementation? I kind of have no clew what its about? is it related to 
the wire protocol or to the implementation of RDS?

Or.