Date: Mon, 01 Apr 1996 13:51:31 -0800 From: David Greenman <davidg@Root.COM> To: Bruce Evans <bde@zeta.org.au> Cc: freebsd-current@freefall.freebsd.org, kuku@gilberto.physik.rwth-aachen.de Subject: Re: calcru: negative time: Message-ID: <199604012151.NAA09740@Root.COM> In-Reply-To: Your message of "Mon, 01 Apr 1996 21:15:40 %2B1000." <199604011115.VAA15805@godzilla.zeta.org.au>
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>>[deleted] >>calcru: negative time: -11929 usec >>calcru: negative time: -3909 usec >>calcru: negative time: -3842 usec >>calcru: negative time: -17709 usec >>calcru: negative time: -3480 usec > >This is caused by hardclock() interrupt latency. The problem is >especially noticable on i586's and i686's because any latency causes the >clock to go backwards; on i386's and i486's, the latency must be > 1 >clock tick (10000 usec) to cause problems. Normally the latency on >i586's is > 0 but < 10 usec and isn't detectable. There must be bugs >elsewhere to cause latencies of more than a few tens of usecs. I'm not convinced that this is a latency problem. The problem has suddenly gotten about 1000 times worse earlier today on both -current and -stable simultaneously...and it's not due to any code changes or load changes. I saw the problem on machines ranging from wcarchive to my X terminal (which is a FreeBSD machine). Note also that as of right now the problem seems to have disappeared again. This looks to me like a strange bug related to the date/ time of year (that it coincides with April Fools Day, has got to be the most amazing thing of all). -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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