Date: Sat, 22 Oct 2005 00:31:41 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, Andre Oppermann <andre@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: Timekeeping [Was: Re: cvs commit: src/usr.bin/vmstat vmstat.c src/usr.bin/w w.c] Message-ID: <20051022002904.P5334@delplex.bde.org> In-Reply-To: <20051021230751.Q5110@delplex.bde.org> References: <27345.1129842256@critter.freebsd.dk> <20051021230751.Q5110@delplex.bde.org>
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On Sat, 22 Oct 2005, Bruce Evans wrote: > On Thu, 20 Oct 2005, Poul-Henning Kamp wrote: >> In summary: CLOCK_MONOTONIC is our best estimate of how many SI >> seconds the system have been runing [3]. > > Actual testing shows that CLOCK_MONOTONIC, or possibly CLOCK_REALTIME > less the boot time, gives a very bad estimate of how long the system has > been running. The difference between these clocks was about 500 seconds > on all systems tested: > > % sledge: > % 1:03PM up 22:45, 1 user, load averages: 0.23, 0.08, 0.02 > % uptime 1 81900 > % uptime 2 82887 > ... > A large fairly machdine-independent differece is hard to explain. I > will reboot after sending this to see if one of the values is much > larger than the uptime when the uptime is < 60 seconds. Please ignore this. It was a stupid bug. After fixing the bug, there were no differences. Bruce
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