On Wed, May 11, 2005 at 02:17:25PM -0300, Juan Carlos Castro y Castro wrote: > Not on Fedora's kernel sources, but with 2.6.11ac7. I based my config on > /boot/config-2.6.11-1.14_FC3 and deat with the additional options with > "make oldconfig". Then I browsed the configuration with "make > menuconfig", just for fun. > > I saw kernel preemption was turned off, so I turned on. Afterwards, I > notice the system is noticeably faster. Bootup is faster. Shutdown is > faster. The Red Hat manu on GNOME pops up WAY faster. OpenOffice.org > loading is faster. I suspect other things are faster too, but I'd have > to time them. Every time this comes up, theres no concrete numbers. Just 'it feels faster'. Given the best that preempt can do is lower the _average_ latency, rather than worse-case latencies which many folks believe, I find it hard to believe it makes a noticable difference. In a blind-test, given two kernels, I'd bet on you not being able to 'feel' which one had preempt enabled. > So my question is: why isn't preemption enabled in the FC3 packaged > kernel? Does it conflict with something I haven't encountered yet? maybe > some esoteric hardware combination? My hardware data is below. It doesn't really buy anything worthwhile, and adds complexity and opportunity for drivers to break. > Another thing: what crucial patch, if any, am I missing by using > 2.6.11ac7 instead of the FC3 packaged kernel? Exec-shield is probably the biggest feature, but there are a bunch of other minor features (restricted /dev/mem, ipw wireless for eg). Dave
