[openib-general] Re: ANNOUNCE: First usable version of userspace verbs

[Michael S. Tsirkin]

Quoting r. Roland Dreier <roland at topspin.com>:
> Subject: ANNOUNCE: First usable version of userspace verbs
> 
> To actually try things out, you can use the ibv_pingpong program
> shipped as part of the libibverbs package.  For example, one one
> system start the server side
> 
>     $ ibv_pingpong
> 
> and on another system start the client by passing the address of the
> server (in this example I use IPv6 over IPoIB):
> 
>     $ ibv_pingpong fe80::202:c901:7fc:c711%ib0
> 
> The pingpong program has a number of options -- run ibv_pingpong -h to
> see a list of the switches you can try.
> 
> The current code is stable for me, but all that means is that my tiny
> selection of tests and test systems has not uncovered any of the bugs
> that are undoubtedly present.  Some of the limitations I know about:
> 

Interestingly, if I rebuild libmthca with -O3 compiler flag, the
pingpong program does not make progress.
Building libibverbs or the test itself with -O3 has no such effect.

# gcc --version
gcc (GCC) 3.3.3 (SuSE Linux)
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

This is somewhat troubling, since exactly which optimisations are set
in -O2 and which in -O3 changes between gcc versions, and so,
unless it turns out to be a compiler bug, we may run into this problem even
with current -O2 in the future.

Roland - can you reproduce this problem?

-- 
MST - Michael S. Tsirkin