Date: Mon, 14 Apr 2008 21:51:42 -1000 (HST) From: Jeff Roberson <jroberson@jroberson.net> To: gnn@freebsd.org Cc: Andrew Gallatin <gallatin@cs.duke.edu>, current@freebsd.org Subject: Re: TSC Timecounter and multi-core/SMP Message-ID: <20080414215057.B959@desktop> In-Reply-To: <m27iezwonx.wl%gnn@neville-neil.com> References: <m2d4oy8n30.wl%gnn@neville-neil.com> <18431.23276.913397.188219@grasshopper.cs.duke.edu> <m27iezwonx.wl%gnn@neville-neil.com>
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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" >
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