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xen-devel
Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been l
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To: |
Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx> |
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Subject: |
Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for) |
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From: |
Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
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Date: |
Mon, 21 Sep 2009 18:02:16 +0100 |
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Cc: |
JeremyFitzhardinge <jeremy@xxxxxxxx>, "Xen-Devel \(E-mail\)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "kurt.hackel@xxxxxxxxxx" <kurt.hackel@xxxxxxxxxx>, "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>, "Nakajima, Jun" <jun.nakajima@xxxxxxxxx>, Alex Williamson <alex.williamson@xxxxxx> |
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[Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for) |
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On 21/09/2009 17:55, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:
> Both Intel and AMD have confirmed that constant_tsc means
> that TSC is consistent across all cores and even across
> multiple sockets; and at least one major system vendor (HP)
> with multi-enclosure "big iron" AMD-based NUMA systems has
> confirmed that TSC is consistent across all nodes. So
> by applying the Xen rendezvous-sync algorithm (that writes
> tsc every second) on such machines, Xen has actually been
> creating a tsc-sync problem, not alleviating one!
Constant_tsc is not even directly a hardware flag. It's a synthetic value
that Linux derives for itself and we inherited. Are vendors really making
guarantees about a flag which they do not directly provide?
-- Keir
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- Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), (continued)
RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Jan Beulich
- RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Dan Magenheimer
- RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Jan Beulich
- RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Dan Magenheimer
- Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Keir Fraser
- Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Keir Fraser
- RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Dan Magenheimer
- Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for),
Keir Fraser <=
- RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Dan Magenheimer
- Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Keir Fraser
- RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Dan Magenheimer
RE: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for), Jan Beulich
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