Date: Sat, 24 Feb 1996 06:21:31 +1100 From: Bruce Evans <bde@zeta.org.au> To: FreeBSD-hackers@FreeBSD.ORG, Mattias.Gronlund@sa.erisoft.se Subject: Re: iostat Message-ID: <199602231921.GAA26638@godzilla.zeta.org.au>
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>Because of the need for better time percision the implementation >curently uses microtime to get the time, but this is'nt realy that >good, because it is possible for it to go backward! So if someone >think that this is something that could be usefull for FreeBSD I >would love to rewrite it for a simple clock that only should be >useful to get delta times from, but with high percisiton. Just fix microtime(). I have seen the clock go backwards a couple of times recently: Feb 20 01:12:39 alphplex /kernel: FreeBSD 2.2-CURRENT #735: Mon Feb 19 07:27:53 EST 1996 Feb 20 01:12:39 alphplex /kernel: bde@alphplex.bde.org:/a/obj/sys/compile/nprof Feb 20 01:12:39 alphplex /kernel: Calibrating clock(s) relative to mc146818A clock ... i586 clock: 132622890 Hz, i8254 clock: 1193105 Hz Feb 20 01:12:39 alphplex /kernel: CPU: Pentium (132.62-MHz 586-class CPU) Feb 20 01:12:39 alphplex /kernel: Origin = "GenuineIntel" Id = 0x52b Stepping=11 Feb 20 01:12:39 alphplex /kernel: Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8> ... Feb 20 03:25:30 alphplex /kernel: calcru: negative time: -70873 usec ... Feb 21 01:33:10 alphplex /kernel: FreeBSD 2.2-CURRENT #738: Tue Feb 20 21:53:27 EST 1996 Feb 21 01:33:10 alphplex /kernel: bde@alphplex.bde.org:/a/obj/sys/compile/nprof Feb 21 01:33:10 alphplex /kernel: Calibrating clock(s) relative to mc146818A clock ... i586 clock: 132622874 Hz, i8254 clock: 1193105 Hz Feb 21 01:33:10 alphplex /kernel: CPU: Pentium (132.62-MHz 586-class CPU) ... Feb 23 19:54:54 alphplex /kernel: calcru: negative time: -314 usec I've never seen this on i486 systems. No time daemons or users running `date' or adjtime() were active. Bruce
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