Date: Sat, 25 Nov 1995 13:25:41 -0800 From: Poul-Henning Kamp <phk@freefall.freebsd.org> To: current@freebsd.org Subject: pentiums, clocks and xntpd: a smoking gun... Message-ID: <17202.817334741@freefall.freebsd.org>
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I remember a thread a little while back about the suitability of the pentiums clock for timekeeping, in particular when we have no way of knowing the actual frequency. I hooked a DCF77 receiver up to my Pentium/133 and here is my findings: My microtime() drifts at a rate of: (7.679466-5.081014)/(76710.567-75815.162) = .002901 this is ten and a half second per hour :-( It is surprisingly close to the ratio of: (133.333333-133)/133 = .002506 If this was the case, then my residual drift would be .000395, or one and a half second per hour. Poul-Henning
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