On Fri, Mar 08, 2013 at 11:54, Tobias Ulmer wrote: > I don't believe it. Someone please compile a kernel with > time make -j$(sysctl -n hw.ncpu) with or and without HT and report > back... (and please, not on a space heater xeon 4 from 2003...)
If you are splitting a core, your process will run about 50% slower. (On Atom, anyway.) But you will be running more processes at once. On a machine with a single core, this is strictly a win. e.g., Compiling a file takes 1 second. Compiling two at the same time with HT takes 1.5 seconds. Compiling two sequentially without HT takes 2 seconds. 1.5 < 2. qed. :) If you have two or more cores, you have to balance this fact with your ability to load all cores.
