PPC 601 and mftb/mftbu - test-drb@ccmp.vtda.org

27 Apr 2010

Hi Cameron,

...
  I'd sort of independently determined this,
although I settled on mfrtcu
 which is spr4-5, IIRC. I'm not sure if it's high enough resolution for this
 task, but as you point out, rdtsc() in the PPC nanojit is a function, so
 it may not be a significant problem. mfrtcu/mfrtcl *should* work on the 603
 and up, right? 
I'm not so sure. I had a look at the rtc. Although I think there's 
user-level access for both the 603 and 601 etc, the problem I see with 
using it is that rtcl counts MOD 10^9 and I'd guess that the use of rdtsc 
assumes MOD 2^64.

-cheers from julz @P