From owner-freebsd-current@FreeBSD.ORG Tue Apr 15 07:51:11 2008 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id AEB6A106566B for ; Tue, 15 Apr 2008 07:51:11 +0000 (UTC) (envelope-from jroberson@jroberson.net) Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.182]) by mx1.freebsd.org (Postfix) with ESMTP id 8B12B8FC1E for ; Tue, 15 Apr 2008 07:51:11 +0000 (UTC) (envelope-from jroberson@jroberson.net) Received: by wa-out-1112.google.com with SMTP id k17so2645618waf.3 for ; Tue, 15 Apr 2008 00:51:11 -0700 (PDT) Received: by 10.114.160.1 with SMTP id i1mr7947785wae.49.1208245871187; Tue, 15 Apr 2008 00:51:11 -0700 (PDT) Received: from ?10.0.1.199? ( [24.94.72.120]) by mx.google.com with ESMTPS id m5sm16351619wag.9.2008.04.15.00.51.09 (version=SSLv3 cipher=OTHER); Tue, 15 Apr 2008 00:51:10 -0700 (PDT) Date: Mon, 14 Apr 2008 21:51:42 -1000 (HST) From: Jeff Roberson X-X-Sender: jroberson@desktop To: gnn@freebsd.org In-Reply-To: Message-ID: <20080414215057.B959@desktop> References: <18431.23276.913397.188219@grasshopper.cs.duke.edu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Andrew Gallatin , current@freebsd.org Subject: Re: TSC Timecounter and multi-core/SMP X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Apr 2008 07:51:11 -0000 On Tue, 15 Apr 2008, gnn@freebsd.org wrote: > At Fri, 11 Apr 2008 08:34:29 -0400 (EDT), > Andrew Gallatin wrote: >> >> >> gnn@freebsd.org writes: >> > Howdy, >> > >> > Is the TSC timecounter synchronized across multiple cores and/or >> > processors? A quick search seems to indicate it's not but I'd like to >> > find a definitive reference on the TSC. >> >> There is a great comment in the OpenSolaris source code talking about >> TSCs and their behavior on SMP systems. See >> http://cvs.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/i86pc/os/timestamp.c >> > > Actually this was a very helpful bit of reading. > > I also believe that at least per processor there is only 1 TSC, that > is, on a 2 or 4 core, all cores share the same TSC. I think we should confirm whether this is the case with earlier opterson. I have seen two processors on the same die out of sync. Jeff > > Best, > George > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >