[openib-general] Gen1 vs Gen2

[Hal Rosenstock]

Hi Scott,

On Thu, 2005-03-31 at 03:49, Scott Bahling wrote:
> What is the general consensus about the Gen1 kernel drivers compared to
> the Gen2 drivers? 

The gen2 drivers are faster (more throughput, lower latency) and are
rapidly catching up in functionality. The driver supports both Tavor and
Arbel, and works in memfree mode. Sinai support will follow. 

> What is the maturity of the Gen2 code relative to Gen1, 

Depends on how you measure maturity. In time since code written, the
code is less mature. However, it is being shaken out by a wider
community and more actively supported than any of the gen1 code. If you
monitor this list, you can see than various gen1 providers have
encouraged their customers in this direction. 

> and are there any features in Gen1 missing from Gen2?

In terms of the HCA driver, there are a few things still missing from
gen2 (OpenIB). Some things which come to mind are SMR and SRQ support.
What ULPs are you interested in ? IPoIB v4/v6 has been there for a while
and adopted upstream. SDP appears to be next. SRP follow thereafter.
There is also an early kDAPL provider soon to be put into the OpenIB
tree.

> I am mostly interested in the kernel module code, but if the Gen2 userspace code is
> much better, and is dependent on the Gen2 kernel code, I would be
> interested to hear about that also.

gen2 userspace code is also better per the same metrics and is dependent
on the kernel code. It is stable based on the testing to date. This is
clearly less mature right now (and also has a few minor things missing
for which there are no known current consumers). It is coming back to
the trunk shortly. User space CM support should also be there shortly.
User space ULPs will follow. There is considerable MPI and uDAPL work
ongoing based on the user verbs branch.

All of the above is not to say that there won't be some bugs to shake
out (your mileage may vary) but most problems found and reported to this
list have been resolved extremely quickly.

-- Hal