From owner-freebsd-questions@FreeBSD.ORG Tue Sep 13 00:15:19 2011 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 62969106566B for ; Tue, 13 Sep 2011 00:15:19 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from asmtpout023.mac.com (asmtpout023.mac.com [17.148.16.98]) by mx1.freebsd.org (Postfix) with ESMTP id 4B5668FC0A for ; Tue, 13 Sep 2011 00:15:19 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; CHARSET=US-ASCII Received: from cswiger1.apple.com ([17.209.4.71]) by asmtp023.mac.com (Oracle Communications Messaging Exchange Server 7u4-20.01 64bit (built Nov 21 2010)) with ESMTPSA id <0LRF009PRQ134Q90@asmtp023.mac.com> for questions@freebsd.org; Mon, 12 Sep 2011 17:15:03 -0700 (PDT) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.4.6813,1.0.211,0.0.0000 definitions=2011-09-12_05:2011-09-12, 2011-09-12, 1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 suspectscore=0 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx engine=6.0.2-1012030000 definitions=main-1109120323 From: Chuck Swiger In-reply-to: <201109122350.RAA21916@lariat.net> Date: Mon, 12 Sep 2011 17:15:02 -0700 Message-id: References: <201109122350.RAA21916@lariat.net> To: Brett Glass X-Mailer: Apple Mail (2.1084) Cc: questions@freebsd.org Subject: Re: Negative ping times with FreeBSD 8.1-RELEASE on older Celeron system X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Sep 2011 00:15:19 -0000 On Sep 12, 2011, at 4:50 PM, Brett Glass wrote: > What's more, it appears that the negative ping times being shown for pings of > localhost are off by about -687 ms, consistently. Any ideas? Your system's timekeeping appears to be busted. Are you running ntpd with "tinker step 0.0" or some home-grown mechanism which might be forcibly stepping the clock rather than skewing it, by any chance? Anyway, the output of: sysctl -a kern.timecounter ...is likely to be informative. Try switching to another clock type, especially ACPI-safe if it hasn't been chosen by default. Your CPU is probably too old to have a power-state invariant TSC, but if you disable SpeedStep, powerd and similar which might change the processor frequency, TSC might work OK also. Regards, -- -Chuck