Date: Fri, 11 Mar 2005 03:19:11 +0000 From: Jason Henson <jason@ec.rr.com> To: freebsd-questions@freebsd.org Cc: freebsd-questions@freebsd.org Subject: Re: Timer setting in FreeBSD Message-ID: <1110511151l.2443l.0l@BARTON> In-Reply-To: <1258079440.20050311032403@wanadoo.fr> (from atkielski.anthony@wanadoo.fr on Thu Mar 10 21:24:03 2005) References: <1258079440.20050311032403@wanadoo.fr>
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On 03/10/05 21:24:03, Anthony Atkielski wrote: > I was reading that recent versions of Linux have increased the base > timer rate (for scheduling and other purposes) from 100 Hz to 1000 =20 > Hz. > I note that FreeBSD apparently will increase this in the same way in > 6.x. >=20 > Is there a way to adjust this value (by configuration, modifying > source, > sysctl, etc.)? Can it be done on a running system? If it can be > changed, are there any significant reasons for adjusting it, and what > are the pros and cons? >=20 > Having 1000 interrupts per second just to keep track of the time =20 > seems > excessive to me in most configurations. Does anyone know how long > this > interrupt takes to service under FreeBSD with specific processors? >=20 > -- > Anthony >=20 >=20 > _______________________________________________ man polling, this is what I use to get the best possible even division =20 with the "Timecounter "i8254" frequency 1193182 Hz quality 0". add something like this to the kernel config. options HZ=3D2299 options DEVICE_POLLING Also you should search the archives first, there is plenty of info on =20 this there. Things like 10000 is a good setting for gigbit ethernet =20 cards, and not needed at all with some network cards that have some =20 hardware/driver combonation that does this automatically. I think the =20 fxp cards do it, and adding polling to fxp cards hurt performance =20 alittle.
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