Subject: Re: Dual core Athlons and unsynced TSCs
From: Lee Revell <rlrevell@joe-job.com>
To: thockin@hockin.org
Cc: Zan Lynx <zlynx@acm.org>, David Lang <dlang@digitalinsight.com>,
       Andreas Steinmetz <ast@domdv.de>,
       Sven-Thorsten Dietrich <sven@mvista.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
In-Reply-To: <20060115162516.GA21791@hockin.org>
References: <1137178855.15108.42.camel@mindpipe>
	 <Pine.LNX.4.62.0601131315310.9821@qynat.qvtvafvgr.pbz>
	 <20060113215609.GA30634@hockin.org>
	 <Pine.LNX.4.62.0601131404311.9821@qynat.qvtvafvgr.pbz>
	 <1137190698.2536.65.camel@localhost.localdomain>
	 <Pine.LNX.4.62.0601131448150.9821@qynat.qvtvafvgr.pbz>
	 <43C848C7.1070701@domdv.de>
	 <Pine.LNX.4.62.0601131701590.9821@qynat.qvtvafvgr.pbz>
	 <1137315165.28041.12.camel@localhost>  <20060115162516.GA21791@hockin.org>
Content-Type: text/plain
Date: Sun, 15 Jan 2006 11:33:36 -0500
Message-Id: <1137342817.25801.17.camel@mindpipe>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 921
Lines: 23

On Sun, 2006-01-15 at 08:25 -0800, thockin@hockin.org wrote:
> On Sun, Jan 15, 2006 at 01:52:44AM -0700, Zan Lynx wrote:
> > A laptop user could also bind a process to a single CPU, and use the
> > scaling min/max values to lock CPU speed to a single value.  The TSC may
> > still stop during HLT, but software must be handling that already.
> > 
> > Wouldn't that provide an accurate TSC?
> 
> monotonic but not linear.  Also remember that the OS will use rdtsc here
> and there, and you can't affine the OS :)
> 

So the options are either to fix the TSC handling on these systems (by
resyncing the TSCs when exiting from HLT), or eliminate the use of rdtsc
by the OS?

Lee

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/