Date: Wed, 15 Jul 1998 13:30:29 +1000 From: Bruce Evans <bde@zeta.org.au> To: jak@cetlink.net Subject: Re: tickadj -t not changing tick Message-ID: <199807150330.NAA22646@godzilla.zeta.org.au>
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>Has anyone else noticed that tickadj -t is broken in -current? It >does not change the tick. I think it changes the kernel `tick' variable. However, this variable is not used for timekeeping in -current. It is only used to calculate timeout intervals. >I can tell by setting the tick to a very low or high value like 9951 >or 10049, and then running ntpdate -b every few minutes to see if the >time step function of ntpdate is compensating for the low/high tick >value. In 2.2.5 it does, but in -current it does not. `tick' shouldn't be changed in any version of 2.2 or -current. Instead, change some of the the lower-level timer variables machdep.i586_freq, machdep.tsc_freq and machdep.i8254_freq using sysctl to make `tick' actually correct. These variables should be set correctly enough by default, just like `tick', but if not, changing them works better than changing `tick' because the change routines propagate necessary changes to associated variables and/or hardware programming. The relevant sysctl variables depend on the the FreeBSD version and configuration: machdep.i8254_freq: always exists, never hurts to set it right, but only essential for it to be right on systems using it for timekeeping (2.2., -current on sub-586's and 586+'s running SMP or APM. machdep.i586_freq: 2.2 name for machdep.tsc_freq. Doesn't hurt to set it right, but not essential for it it be right. machdep.tsc_freq: -current only, must be right if it is used for timekeeping. It is used on 586+'s not running SMP or APM. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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