From: Olaf Hering <olaf@aepfle.de>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: "Tim Deegan" <tim@xen.org>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Wei Liu" <wei.liu2@citrix.com>,
"George Dunlap" <George.Dunlap@eu.citrix.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Ian Jackson" <ian.jackson@eu.citrix.com>,
"Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
xen-devel@lists.xen.org, "Julien Grall" <julien.grall@arm.com>,
"Jan Beulich" <jbeulich@suse.com>
Subject: Re: [PATCH v5] new config option vtsc_tolerance_khz to avoid TSC emulation
Date: Thu, 29 Mar 2018 10:58:34 +0200 [thread overview]
Message-ID: <20180329085834.GI30726@aepfle.de> (raw)
In-Reply-To: <20180329082545.sxx57zod4rttxqc6@MacBook-Pro-de-Roger.local>
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On Thu, Mar 29, Roger Pau Monné wrote:
> AFAICT in the chunk above you will disable vtsc without checking if
> the hardware supports TSC scaling, which leads to inaccurate TSC values
> on hardware that could provide accurate results without the software
> emulation overhead.
Is that really the case? Maybe I get the logic wrong, but what I see is:
what ever my change does, or if a HVM domain runs on a host with scaling
feature, disable vtsc. hvm_get_tsc_scaling_ratio has no side effects.
Isnt the purpose to not emulate vtsc if the hardware supports scaling?
Olaf
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next prev parent reply other threads:[~2018-03-29 8:58 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-27 9:26 [PATCH v5] new config option vtsc_tolerance_khz to avoid TSC emulation Olaf Hering
2018-03-28 16:27 ` Wei Liu
2018-03-28 16:49 ` George Dunlap
2018-03-28 16:52 ` Wei Liu
2018-03-28 17:07 ` George Dunlap
2018-03-28 17:13 ` Wei Liu
2018-03-29 8:04 ` Jan Beulich
2018-03-29 8:17 ` Olaf Hering
2018-03-29 8:35 ` Jan Beulich
2018-03-29 9:23 ` Olaf Hering
2018-03-29 9:56 ` Jan Beulich
2018-03-29 10:05 ` Olaf Hering
2018-03-29 10:36 ` Jan Beulich
2018-03-29 8:25 ` Roger Pau Monné
2018-03-29 8:32 ` Olaf Hering
2018-03-29 8:53 ` Jan Beulich
2018-03-29 8:58 ` Olaf Hering [this message]
2018-03-29 9:06 ` Roger Pau Monné
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