Date: Sat, 22 Oct 2005 02:25:01 +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: <20051022021817.X5902@delplex.bde.org> In-Reply-To: <30805.1129910750@critter.freebsd.dk> References: <30805.1129910750@critter.freebsd.dk>
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On Fri, 21 Oct 2005, Poul-Henning Kamp wrote: > In message <20051022011020.T5554@delplex.bde.org>, Bruce Evans writes: > >> How do you resync laptops after suspending them for long enough for >> the clock to drift? Use ntpd and let it step, or use ntpd -x and let >> it take hours to resync? The right thing to do is step the clocks to >> the current time immediately so that they are correct while the system >> is actually being used. > > Ahh, and now we get into interesting territory: What _is_ the > definition of uptime for a laptop which has been suspended ? > > No matter which way you turn, there are dragons... >> I certainly care about errors of 1 microsecond (although I don't need >> to), and just remembered that I use stepping to fix up the clock after >> sitting in ddb with the clock stopped. This reduces the error in the >> real time clock to ~1 microsecond per second stopped, but gives an error >> of 1 second per second stopped in the monotonic time and the boot time. >> Here the correct treatment is to jump the monotonic time forward and >> not touch the boot time. > > Again, if you have been sitting in DDB, what exactly is the definition > of "uptime" ? This is clear. The system is up while it is sitting in ddb. It's actually more active then average then, since doesn't idle or halt :-). Bruce
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