[openib-general] RFC: detecting duplicate MAD requests

[Sean Hefty]

Hal Rosenstock wrote:
>>This brings up a concern.  There doesn't seem to be a limit to the number of 
>>received MADs that can be queued for a user.  Should we have such a limit?
> 
> 
> How are MADs counted ? Is a multisegment MAD 1 MAD or multiple MADs ? If
> the latter, it seems problematic to limit this as the response to a get
> response might be very large.

I could go either way, or use a hybrid of some sort  Counting a multisegment MAD 
as 1 MAD might be a little easier.  We could also allow something like 100 
segments, or at least 1 reassembled MAD.  So, the user could have 100 single 
segment MADs, 50 2-segment MADs, etc.

Without some sort of restriction, a userspace app that's slow to pull receive 
MADs from the kernel would result in consuming a large amount of kernel memory.

- Sean