Hey Henry. I think they will be little difference in practice. Perhaps a cycle less latency, but that is hard to say as I'm not really sure what was going on in the OPB-IPIF bridge. In principle the OPB-IPIF bridge might support bursting(for DMA) a little better. But I'm pretty sure DMA isn't used on software registers or anywhere else for that matter (certainly not on ROACH). The difference should only be in utilization.
I've had a close look at the extra features in the old software registers and they are entirely superfluous. These could be removed on iBOB on BEE2 base package for a little extra saving there. Cheers, David On 21 April 2010 22:12, Henry Chen <[email protected]> wrote: > Hi Dave, > > Those are some nice savings! Do you have a feel for whether there > are any performance impacts, for better or worse, or should it be > about neutral? > > Thanks, > Henry > > > On 4/19/2010 8:26 AM, David George wrote: > >> Hi Aaron. >> >> Nice work! Are there any tantalizing details you might be able to >> pass along as to what changes made the difference? I always like the >> lessons-learned section... >> >> >> Sure, there were two things optimized: >> >> The first was an unnecessary OPB to IPIF bridge. This was an artefact from >> using the EDK GUI to create OPB modules. Rather than using this mechanism, I >> wrote the module with a direct OPB connection (which is simpler and easier >> to follow in my opinion) >> The other optimization was to trim the extras that were accessible from >> software (these included locks and status bits). I'm not sure that these >> features were ever used and are definitely not required for BORPH. I think >> that the registers are now as simple as they could be. >> >> Cheers, >> David >> >> >> >> On Mon, Apr 19, 2010 at 7:34 AM, David George >> <[email protected] <mailto:[email protected]>> wrote: >> > Greetings All. >> > I've done some optimization on the ROACH software registers and >> it has >> > turned out to be pretty fruitful. >> > The powerpc to simulink register utilization has been reduced >> from 99 to 26 >> > slices (3.8x less). >> > The simulink to powerpc register utilization has been reduced >> from 72 to 25 >> > slices (2.9x less). >> > This should help out with utilization if you use a lot of >> software registers >> > (eg the packetized correlator). >> > These changes apply from svn revision 2945. >> > Cheers, >> > David >> > -- >> > David George >> > Karoo Array Telescope >> > Tel: +27 21 531-7282 >> > Email: [email protected] <mailto:[email protected]> >> >> > >> >> >> >> -- >> Aaron Parsons >> >> 510-406-4322 (cell) >> Campbell Hall 523, UCB >> >> >> >> >> -- >> David George >> Karoo Array Telescope >> Tel: +27 21 531-7282 >> Email: [email protected] <mailto:[email protected]> >> > -- David George Karoo Array Telescope Tel: +27 21 531-7282 Email: [email protected]
