[ENBD] Enbd over SCI

[Arne Wiebalck]

hi peter,

enbd now seems to work over the SCI network technology. as you
proposed at our meeting here in heidelberg, I adapted the functions in the
stream.c interface to SCI.

using the API provided by Dolphin (www.dolphinics.no)
I implemented sci read and write functionality, which performed not too
bad in stand alone testing (around 33 MB/s with 4k blocks and 110 MB/s
with 1M blocks, while cpu load / MB ratio is better than for TCP/IP).
I also adpated the negotiation in nbd-client/server to talk about SCI
segments.

some part of this negotiation is still done over TCP/IP, but the "fresh
socket" is an sci segment. after that the client goes into the main loop.
mke2fs works and I could transfer several GB of data with your nbd-test
program using the SCI stream. seems to work :)

performance is not impressing currently: 16 MB/sec on read with 4k
(should be the server's disk speed - ok), 4.5 MB/sec on write, also with
4k blocks (don't know yet what's stopping me here). cpu load ranges from
15-30%, but part of it is due to nbd-test generating the patterns.
for the rest I hope I can somehow improve that ...

not implemented yet are multiple streams and some others things.
I'll work on that the next days.

if you're interested I'll keep you informed how things are going.

best regards
arne










**********************************************************************
 Arne Wiebalck                        Kirchhoff Institute for Physics
                                           Technical Computer Science
                                                     Schroederstr. 90
                                                   D-69120 Heidelberg

 e-mail: wiebalck@kip.uni-heidelberg.de      Tel.: (+49) 6221/54-4362
 web   : http://www.kip.uni-heidelberg.de    Fax.: (+49) 6221/54-4345
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