Date: Thu, 02 Jan 2003 10:59:30 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Marcel Moolenaar <marcel@FreeBSD.org> Cc: Perforce Change Reviews <perforce@freebsd.org> Subject: RE: PERFORCE change 23029 for review Message-ID: <XFMail.20030102105930.jhb@FreeBSD.org> In-Reply-To: <200301012203.h01M3nKH028011@repoman.freebsd.org>
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On 01-Jan-2003 Marcel Moolenaar wrote: > http://perforce.freebsd.org/chv.cgi?CH=23029 > > Change 23029 by marcel@marcel_nfs on 2003/01/01 14:03:34 > > While here, reload cr.itm (interval timer match register) > based on the old value of cr.itm and not cr.itc (interval > timer counter). The value of cr.itc is non-deterministicly > close to the value of cr.itm at the time of the interrupt. > The SDM clearly states that they are not guaranteed to be > identical, even though the interrupt is triggered when > cr.itc equals cr.itm). Reloading cr.itm based on the value > of cr.itc will therefore introduce a non-deterministic error > in the clocks. This will also reduce clock skew due to > interrupt latency. Cool. Peter says the Linux code does something similar but goes to extra efforts to handle the case of missing entire ticks and what not.w -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe p4-projects" in the body of the message
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