[ofa-general] IPOIB CM (NOSRQ) patch -memory footprint

[Roland Dreier]

 > By default, cap the NOSRQ memory usage to 1GB. The default recvq_size
 > is set to 128. Therefore for 64KB packets this would imply a maximum of
 > 128 endpoints.

1 GB is a pretty eye-popping amount to tie up in receive buffers.

 > -The NOSRQ limit of 1GB is also made a module parameter.

There are too many module parameters already I think...

 > -Currently we allocate a default of 64KB for the ring buffer elements,
 > and this buffer size is not linked to the mtu. In the future, we could
 > allocate buffers based on the mtu and link that into the computation of
 > the memory cap. This way customers who might want to use a smaller mtu
 > could use a larger number of endpoints, or a larger recvq_size without
 > exceeding the memory cap.

It would be nice, but to handle increasing the MTU, you need some way
to handle the receives you already posted (which would be too small
all of a sudden).

 - R.