From: Keir Fraser <keir.fraser@eu.citrix.com>
To: "dan.magenheimer@oracle.com" <dan.magenheimer@oracle.com>,
"Xen-Devel (E-mail)" <xen-devel@lists.xensource.com>
Cc: Dave Winchell <dwinchell@virtualiron.com>
Subject: Re: Re: [PATCH] clocksource=tsc
Date: Fri, 18 Jul 2008 16:00:57 +0100 [thread overview]
Message-ID: <C4A66EB9.244DA%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <20080718085606203.00000001344@djm-pc>
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
next prev parent reply other threads:[~2008-07-18 15:00 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-12 21:38 [PATCH] clocksource=tsc Dan Magenheimer
2008-07-13 3:59 ` Dan Magenheimer
2008-07-14 9:24 ` Keir Fraser
2008-07-14 17:59 ` Dan Magenheimer
2008-07-15 0:35 ` Tian, Kevin
2008-07-17 23:47 ` Dan Magenheimer
2008-07-15 13:05 ` Keir Fraser
2008-07-15 14:44 ` Dan Magenheimer
2008-07-15 15:08 ` Keir Fraser
2008-07-15 15:46 ` Dan Magenheimer
2008-07-15 16:04 ` Dan Magenheimer
2008-07-16 1:15 ` Dan Magenheimer
2008-07-16 4:11 ` Dan Magenheimer
2008-07-16 12:43 ` Dan Magenheimer
2008-07-16 12:49 ` Keir Fraser
2008-07-16 13:43 ` Dan Magenheimer
2008-07-16 15:42 ` Dan Magenheimer
2008-07-16 19:32 ` Keir Fraser
2008-07-17 23:05 ` Dan Magenheimer
2008-07-18 7:24 ` Keir Fraser
2008-07-18 11:01 ` Keir Fraser
2008-07-18 11:10 ` Keir Fraser
2008-07-18 14:19 ` Dan Magenheimer
2008-07-18 14:29 ` Keir Fraser
2008-07-18 14:56 ` Dan Magenheimer
2008-07-18 15:00 ` Keir Fraser [this message]
2008-07-18 16:51 ` Dan Magenheimer
2008-07-18 19:28 ` Keir Fraser
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