[rds-devel] RDS IB transport software flow control?
Or Gerlitz
ogerlitz at voltaire.com
Wed Nov 7 06:49:24 PST 2007
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.
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