From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: Re: [PATCH] clocksource=tsc
Date: Fri, 18 Jul 2008 16:00:57 +0100
Message-ID: <C4A66EB9.244DA%keir.fraser@eu.citrix.com>
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Cc: Dave Winchell <dwinchell@virtualiron.com>
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On 18/7/08 15:56, "Dan Magenheimer" <dan.magenheimer@oracle.com> wrote:

> It appears that, for clocksource=tsc, as long as both
> read_platform_stime() and get_s_time() are returning
> scaled-tsc there can be no divergence.
> 
> The issue with generating fresh time records every
> few seconds is that it unnecessarily introduces jitter
> into an otherwise ideal timesource.

I don't think this is necessarily true. If we write code to generate
accurate time records specifically for clocksource=tsc then we should easily
get accuracy down to a couple of parts per billion. This is certainly a more
pragmatic solution than extending the guest time interfaces. I am at least
coming round to the fact that the changes required in Xen's time.c are going
to have to be a bit more drastic than I first hoped.

 -- Keir