Date: Fri, 2 Aug 2002 16:12:12 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Martin Karsten <Martin.Karsten@KOM.tu-darmstadt.de> Cc: freebsd-net@FreeBSD.ORG Subject: Re: device polling breaks ntp? Message-ID: <20020802161212.F90290@iguana.icir.org> In-Reply-To: <200208021516.g72FG4M18743@KOM.tu-darmstadt.de>; from Martin.Karsten@KOM.tu-darmstadt.de on Fri, Aug 02, 2002 at 05:16:03PM %2B0200 References: <200208021516.g72FG4M18743@KOM.tu-darmstadt.de>
next in thread | previous in thread | raw e-mail | index | archive | help
DEVICE_POLLING can basically introduce a variance of up to 1/HZ on the delivery of network packets. Then i have no idea on how ntpd is affected by variance in the samples. cheers luigi On Fri, Aug 02, 2002 at 05:16:03PM +0200, Martin Karsten wrote: > I have reasons to believe that network device polling breaks the > functionality of ntpd. I'm using FreeBSD 4.5 and ntp-4.1.71. > > When device polling is enabled *before* ntpd is started (particularly, when > device polling is enabled at boot time), ntpd seems to be unable to properly > synchronize with a reference clock. While I understand that the increased > packet delay variance introduced by network device polling might affect > ntpd's algorithms to estimate the network delay, it also seems to break > clock synchronization with a locally attached GPS-receiver. > > When network device polling is enabled *after* ntpd is started, it does not > cause immediate problems and I have not further investigated what exactly > happens in this case. > > In any case, disabling sysctl kern.polling.enable and restarting ntpd > results in proper operation of ntpd. > > Is this behaviour known and is there a workaround? > > Thanks, > Martin > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20020802161212.F90290>