From: Qin Li <qin.l.li@oracle.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xensource.com, Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: Could you please answer some questions regarding Solaris PVHVM pvclock support.
Date: Fri, 28 Feb 2014 11:27:00 +0800 [thread overview]
Message-ID: <53100204.1050801@oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1402271253000.31489@kaball.uk.xensource.com>
于 2014/2/27 21:03, Stefano Stabellini 写道:
>> >I guest linux guest will do the same thing, rdtsc() fetch current timestamp from current running vCPU, TSC out-of-sync issue is still there.
>> >It seems to me pvclock finally fix the time drift issue just because the workaround enforced as above, right?
> First you should know that TSC is not always guaranteed to be
> synchronized across multiple processors, especially on older systems.
> On "TSC-safe" systems, Xen would export a consistent TSC to guests, by
> setting the vtsc offset and scale appropriately.
Stefano,
Is there a easy way to check whether the system is "TSC-safe"? Do you
mean "X86_FEATURE_TSC_RELIABLE" bit in "boot_cpu_data.x86_capability"?
Thanks,
Michael
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next prev parent reply other threads:[~2014-02-28 3:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <52D6566C.5050302@oracle.com>
2014-01-16 12:17 ` Could you please answer some questions regarding Solaris PVHVM pvclock support Stefano Stabellini
2014-01-24 0:21 ` Mukesh Rathor
2014-02-26 11:52 ` Qin Li
2014-02-27 13:03 ` Stefano Stabellini
2014-02-28 3:27 ` Qin Li [this message]
2014-02-28 15:04 ` Stefano Stabellini
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