On Tue, Mar 23, 2010 at 4:11 PM, Dan Kegel <d...@kegel.com> wrote: > Not as exciting an improvement as I'd hoped: > > 4 GB RAM > Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz > make -j5 > real 7m35.985s > user 24m54.741s > sys 3m15.628s > > 6 GB RAM > model name : Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz > make -j9 > real 4m39.577s > user 30m43.651s > sys 2m30.109s
Even though Nehalem is a better architecture, you don't get the 2x (or better) speed up because the extra 4 cores are from hyperthreading. With 8 real Nehalem cores and -j9, I got 3m24s. With 8 cores + hyperthreading, I get 2m49s. And now to figure out how much electricity I just used... ;-)