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<br>> Date: Sun, 8 Mar 2009 19:56:57 -0700<br>> Subject: Re: Clock problems<br>> From: coderman@gmail.com<br>> To: or-talk@freehaven.net<br>> <br>> On Sun, Mar 8, 2009 at 6:16 PM, downie - <downgeoff2@hotmail.com> wrote:<br>> >...<br>> > "[warn] Your system clock just jumped 160 seconds forward; assuming<br>> > established circuits no longer work."<br>> > There are big blocks of these errors occuring 3 minutes 40 seconds or so<br>> > apart, for 3 hours.<br>> > The reported clock jump is always 150-170 seconds, and always forwards.<br>> ...<br>> <br>> this sounds like the expected behavior of ntpd issuing adjtime() calls<br>> to slowly bring your clock skew down to current time. this can take<br>> hours depending on how large of an adjustment is needed.<br>> <br>> is the computer off for a longer period of time than usual when such<br>> behavior occurs?<br><br>It had been on for a couple of days before the latest rash of warnings, and Tor had been running for just over an hour after a daily shutdown of an hour.<br> A few days ago I had some overnight broadband outages.<br>FWIW the clock synchronises to Apple's server, I'm not sure how often, and I haven't had any warnings about being out of sync.<br><br><br><br><br>> from OSX adjtime man page:<br>> <br>> DESCRIPTION<br>> Adjtime() makes small adjustments to the system time, as returned by<br>> gettimeofday(2), advancing or retarding it by the time specified by<br>> the timeval delta. If delta is negative, the clock is slowed down by<br>> incrementing it more slowly than normal until the correction is<br>> complete. If delta is positive, a larger increment than normal is<br>> used. The skew used to perform the correction is generally a fraction<br>> of one percent. Thus, the time is always a monotonically increasing<br>> function...<br>><br><br>Hmm, I'll have to take that on trust - I have no manpages for adjtime or gettimeofday.<br>Those commands aren't recognised.<br><br> also, ntpd / ntpdate may also perform similar incremental adjustment themselves:<br>> <br>> """<br>> [ntpd|ntpdate may] step the time using settimeofday(2) if the offset<br>> is greater than +-128 ms. Note that, if the offset is much greater<br>> than +-128 ms in this case, it can take a long time (hours) to slew<br>> the clock to the correct value. During this time, the host should not<br>> be used to synchronize clients.<br>> """<br>> <br>> best regards,<br><br>Thank you,<br>GD<br><br /><hr />HotmailŪ is up to 70% faster. Now good news travels really fast. <a href='http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_HM_70faster_032009' target='_new'>Find out more.</a></body>
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