From owner-freebsd-hackers@FreeBSD.ORG Tue Sep 13 12:19:11 2011 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 82ABA106564A for ; Tue, 13 Sep 2011 12:19:11 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 59D1F8FC0A for ; Tue, 13 Sep 2011 12:19:11 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 12A3346B2E; Tue, 13 Sep 2011 08:19:11 -0400 (EDT) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 945EF8A02E; Tue, 13 Sep 2011 08:19:10 -0400 (EDT) From: John Baldwin To: freebsd-hackers@freebsd.org Date: Tue, 13 Sep 2011 08:17:42 -0400 User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110617; KDE/4.5.5; amd64; ; ) References: <201109111852.MAA08146@lariat.net> <14112_1315854090_4E6E570A_14112_184_1_D9B37353831173459FDAA836D3B43499C803FA06@WADPMBXV0.waddell.com> <201109122153.PAA20860@lariat.net> In-Reply-To: <201109122153.PAA20860@lariat.net> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201109130817.42232.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (bigwig.baldwin.cx); Tue, 13 Sep 2011 08:19:10 -0400 (EDT) Cc: Brett Glass Subject: Re: Negative ping times with FreeBSD 8.1-RELEASE on older Celeron system X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Sep 2011 12:19:11 -0000 On Monday, September 12, 2011 5:53:39 pm Brett Glass wrote: > More information regarding the odd behavior I'm seeing. Turns out > that packets do not even need to leave the machine for it to > report large negative ping times, on the order of more than half > a second. (See below.) Clearly something is odd about timekeeping > in this system (SiS motherboard chipset, PII-generation Celeron > but still effectively a "686") which was not a problem when it was > running FreeBSD 4.11-RELEASE (as it was before). Any ideas? 4.x didn't support the ACPI timer. I would look at the kern.timecounter sysctls. Maybe try forcing it to use the TSC. -- John Baldwin