Date: Thu, 6 May 2004 16:36:41 -0500 (CDT) From: "Paul Seniura" <pdseniura@techie.com> To: <freebsd-current@freebsd.org> Subject: low HZ value causes "Time Warp Bug" (re: this Puny Pentium2 suddenly became 45% slower!) Message-ID: <20040506213641.1C6C25CD1@techpc04.okladot.state.ok.us> In-Reply-To: <20040506171135.1ADEA5CB5@techpc04.okladot.state.ok.us> References: <20040506171135.1ADEA5CB5@techpc04.okladot.state.ok.us>
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It seems this bug happens when the HZ value goes below 16 (either by compiling 'options HZ=' in kernel or setting sysctl 'kern.hz=' in /boot/loader.conf). The computed 'ticks' value becomes too large for 2-byte int producing crazy overflowed numbers elsewhere. The crazyness extends to human clocks such as what KDE uses. I mean it was visibly speeding up and showing time to go home before it was 'really' lunchtime! Time warp!! Something needs to check for overflow, but I bet whatever this field is cannot easily be widend past 2-byte int? I guess I will file a PR on this. -- thx, Paul Seniura.
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