On Sun, 25 Nov 2007, Stephen Montgomery-Smith wrote:
(Also when I run 4 threads with 2 cpus, each with hyperthreading, it goes 2.5 to 3 times faster - surprising since hyperthreading gets quite bad press for its performance improvements - I should add that Linux didn't do at all well at taking advantage of hyperthreading, running at the same speed as with 2 threads.)
I've seen gradual improvements both in our ability to manage HTT and HTT itself. One of the things that gave HTT a particularly bad reputation was that it was first introduced in the P4 Xeon CPU line from Intel, and that line had extortionately expensive synchronization instructions compared to either prior or later CPU lines. As a result, even a small amount of synchronization (read: kernel locking) quickly ate any benefits of potential parallelism. More recent CPUs have managed to reduce "extionate" to "relatively expensive", which is much more manageable.
Robert N M Watson Computer Laboratory University of Cambridge _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
