On Wed, 2005-05-11 at 17:01 -0400, Dave Jones wrote: > 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 > > > 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). hey dave! thanks for that thoughtful reply. i've been curious about that for a long time, as well. while i'm thinking of it, thanks for all those thoughtful replies you've given. i've appreciated the thought that went into them on a number of occasions. sure would be fun to try some timed tests with and without. wish i had the h/w to do it on. :-( dave, can you tell us a little more about the "...opportunity for drivers to break...." comment? i'd just like to understand a bit more about the implications of it. thanks! john
