Stijn Hoop wrote: > On Mon, Dec 02, 2002 at 11:49:03AM -0600, Mike Silbersack wrote: > > The time select() takes should be directly related to your system's hz > > setting. The default for FreeBSD is 100, which means that the interrupt > > timer will fire every 10ms. If you want to play with that, edit > > /etc/sysctl.conf and set kern.hz="1000", which should give you 1 ms > > accuracy. > > With the mentioned change of /etc/sysctl.conf to /boot/loader.conf, I am > indeed seeing much better times on this 'benchmark'. See attached log. Not > only the _select_sleep method benefits from this. What are the reasons *not* > to do this?
Increased context switch overhead. > > As to why Linux may appear "better"... I believe that Linux defaults to > > hz=100, but that the default switched to hz=1000 sometime in the recent > > past. > > And why don't we do the same? (I suspect this is related to the question > above :) Increased context switch overhead. > > To answer your final question: Sleep accuracy doesn't matter to most > > applications, but I'm sure counterexamples could be found. > > Such as emulators :) Actually, for the case you are talking about, your emulator should be using aggregate instead of discrete timeouts, and you would not be having a problem. It's not useful to do 100 1ms timeouts to achieve a 100ms timeout, when you can ask for a single 100ms timeout. I would count this as a bug in your emulator. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
