Date: Wed, 19 Jul 2000 11:42:35 -0600 From: Warner Losh <imp@village.org> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: mark@grondar.za, current@FreeBSD.ORG, phk@FreeBSD.ORG Subject: Re: randomdev entropy gathering is really weak Message-ID: <200007191742.LAA82840@harmony.village.org> In-Reply-To: Your message of "Tue, 18 Jul 2000 18:01:00 %2B0200." <200007181601.SAA02045@Magelan.Leidinger.net> References: <200007181601.SAA02045@Magelan.Leidinger.net>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <200007181601.SAA02045@Magelan.Leidinger.net> Alexander Leidinger writes: : systems which have a more or less precise clock attached (e.g. GPS or : atomic clocks which sync the system clock via nptd)? And what are the : numbers for this solution (for those people which are interested in : numbers to be their own judge)? I can tell you right now that the variation between GPS and a good cesium clock is on the order of +- 25ns. With nanosecond resolution, this gives you about 5 bits. The variation of the system clock when synchronized to the GPS receiver is on the order of +-10us as measured with a parallel port interrupt and a pps line from the gps receiver. The pps interrupt is measured using a fast interrupt (we hacked ppc to do fast interrupts for this), so the latency is fairly small and fairly constant. I don't have datasets that I can point people at, however. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200007191742.LAA82840>