Date: Thu, 16 Aug 2012 02:40:09 GMT From: dfilter@FreeBSD.ORG (dfilter service) To: freebsd-bugs@FreeBSD.org Subject: Re: kern/156481: commit references a PR Message-ID: <201208160240.q7G2e9Uo045960@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR kern/156481; it has been noted by GNATS. From: dfilter@FreeBSD.ORG (dfilter service) To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/156481: commit references a PR Date: Thu, 16 Aug 2012 02:35:54 +0000 (UTC) Author: imp Date: Thu Aug 16 02:35:44 2012 New Revision: 239320 URL: http://svn.freebsd.org/changeset/base/239320 Log: Limit popcorn limit to something sane (either 2ns or 2 ticks if that's longer). PR: 156481 Submitted by: Ian Lepore Modified: head/sys/kern/kern_ntptime.c Modified: head/sys/kern/kern_ntptime.c ============================================================================== --- head/sys/kern/kern_ntptime.c Thu Aug 16 00:53:23 2012 (r239319) +++ head/sys/kern/kern_ntptime.c Thu Aug 16 02:35:44 2012 (r239320) @@ -832,8 +832,15 @@ hardpps(tsp, nsec) * discarded. otherwise, if so enabled, the time offset is * updated. We can tolerate a modest loss of data here without * much degrading time accuracy. - */ - if (u_nsec > (pps_jitter << PPS_POPCORN)) { + * + * The measurements being checked here were made with the system + * timecounter, so the popcorn threshold is not allowed to fall below + * the number of nanoseconds in two ticks of the timecounter. For a + * timecounter running faster than 1 GHz the lower bound is 2ns, just + * to avoid a nonsensical threshold of zero. + */ + if (u_nsec > lmax(pps_jitter << PPS_POPCORN, + 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) { time_status |= STA_PPSJITTER; pps_jitcnt++; } else if (time_status & STA_PPSTIME) { _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201208160240.q7G2e9Uo045960>