From: Ian Campbell <ian.campbell@citrix.com>
To: Peng Fan <van.freenix@gmail.com>, Jan Beulich <JBeulich@suse.com>
Cc: Julien Grall <julien.grall@citrix.com>,
xen-devel@lists.xenproject.org,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
David Vrabel <david.vrabel@citrix.com>,
George Dunlap <george.dunlap@citrix.com>
Subject: Re: [RFC V2] xen: interface: introduce pvclk interface
Date: Wed, 20 Jan 2016 14:49:13 +0000 [thread overview]
Message-ID: <1453301353.26343.125.camel@citrix.com> (raw)
In-Reply-To: <20160120143719.GD10911@linux-7smt.suse>
On Wed, 2016-01-20 at 22:37 +0800, Peng Fan wrote:
>
> > Then (also considering the set of commands you propose) what
> > use is the clock to the guest? It can't get events from it, it can't
> > read its current value, all it can is get/set its rate, enable/disable,
> > and prepare/unprepare it. I may be lacking some ARM knowledge
> > here, but all of this looks pretty odd to me.
Perhaps it helps to mention that these are the clocks which drive the
silicon in the device IP (in the "I have a 2GHz processor" sense), rather
than anything to do with time or (s/w visible) events.
On x86 these are not often under OS control, but on ARM it is common for
the network of clocks and associated muxers and dividers to be made
available to the OS in quite a fine grained manner and for
unused/unnecessary clocks to be disabled or under utilised ones to be
scaled to save power etc.
Ian.
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next prev parent reply other threads:[~2016-01-20 14:49 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-20 8:31 [RFC V2] xen: interface: introduce pvclk interface Peng Fan
2016-01-20 9:05 ` Juergen Gross
2016-01-20 9:25 ` Peng Fan
2016-01-20 10:16 ` Jan Beulich
2016-01-20 10:40 ` Juergen Gross
2016-01-20 11:48 ` Peng Fan
2016-01-20 12:11 ` Juergen Gross
2016-01-20 14:13 ` Peng Fan
2016-01-20 10:14 ` Jan Beulich
2016-01-20 11:40 ` Peng Fan
2016-01-20 12:01 ` Jan Beulich
2016-01-20 14:05 ` Peng Fan
2016-01-20 14:16 ` Jan Beulich
2016-01-20 14:37 ` Peng Fan
2016-01-20 14:49 ` Ian Campbell [this message]
2016-01-20 14:52 ` Jan Beulich
2016-01-21 1:29 ` Peng Fan
2016-01-21 7:53 ` Jan Beulich
2016-01-21 8:59 ` Peng Fan
2016-01-21 10:19 ` Ian Campbell
2016-01-21 11:55 ` Peng Fan
2016-01-21 12:26 ` Ian Campbell
2016-01-21 12:35 ` Peng Fan
2016-01-21 12:49 ` Ian Campbell
2016-01-22 2:19 ` Peng Fan
2016-01-23 15:26 ` Peng Fan
2016-01-21 12:55 ` Stefano Stabellini
2016-01-21 13:11 ` Ian Campbell
2016-01-21 16:11 ` Stefano Stabellini
2016-01-22 2:51 ` Peng Fan
2016-01-21 10:21 ` Jan Beulich
2016-01-21 12:06 ` Peng Fan
2016-01-21 12:52 ` Jan Beulich
2016-01-22 1:56 ` Peng Fan
2016-01-22 7:36 ` Jan Beulich
2016-01-22 9:27 ` Peng Fan
2016-01-22 10:25 ` Jan Beulich
2016-01-22 12:12 ` Peng Fan
2016-01-22 12:33 ` Jan Beulich
2016-01-22 13:55 ` Stefano Stabellini
2016-01-20 12:06 ` Stefano Stabellini
2016-01-20 12:27 ` Ian Campbell
2016-01-20 13:52 ` Peng Fan
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