From: Paul Durrant <Paul.Durrant@citrix.com>
To: Andrew Cooper <Andrew.Cooper3@citrix.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Jan Beulich <jbeulich@suse.com>
Subject: Re: [PATCH 6/7] x86/viridian: make the threshold for HvNotifyLongSpinWait tunable
Date: Mon, 20 Mar 2017 17:07:05 +0000 [thread overview]
Message-ID: <683401bdce86427ab6f236d3ccac89ec@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <2bf886c7-03f9-eb71-cc60-741e8df8b8e1@citrix.com>
> -----Original Message-----
> From: Andrew Cooper
> Sent: 20 March 2017 17:03
> To: Paul Durrant <Paul.Durrant@citrix.com>; xen-devel@lists.xenproject.org
> Cc: Jan Beulich <jbeulich@suse.com>
> Subject: Re: [PATCH 6/7] x86/viridian: make the threshold for
> HvNotifyLongSpinWait tunable
>
> On 17/03/17 09:57, Paul Durrant wrote:
> > The current threshold before the guest issues the hypercall is, and always
> > has been, hard-coded to 2047. It is not clear where this number came
> > from so, to at least allow for ease of experimentation, this patch makes
> > the threshold tunable via the Xen command line.
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>
> This is one example of a configuration option which I'd prefer to see
> done with the (planned) new CPUID interface.
>
> The value here doesn't have any impact on the hypervisor, so a
> configuration option is free to be chosen entirely by the toolstack, and
> would also become inherently per-domain configuration rather than global.
>
> Can I talk you into deferring this change until the CPUID interface is
> sorted, to avoid introducing yet another command line option?
>
I don't really want to wait for something with no definite timescale. I don't see any harm in adding this and then stating it can be overridden by per-domain CPU policy later on. Presumably there's a bunch of other stuff where this would be the case.
Paul
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next prev parent reply other threads:[~2017-03-20 17:07 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-17 9:57 [PATCH 0/7] x86/viridian updates Paul Durrant
2017-03-17 9:57 ` [PATCH 1/7] x86/viridian: update to version 5.0a of the specification Paul Durrant
2017-03-20 11:27 ` Jan Beulich
2017-03-20 11:43 ` Paul Durrant
2017-03-20 11:54 ` Jan Beulich
2017-03-17 9:57 ` [PATCH 2/7] x86/viridian: fix xen-hvmcrash when vp_assist page is present Paul Durrant
2017-03-20 11:36 ` Jan Beulich
2017-03-20 11:50 ` Paul Durrant
2017-03-20 13:42 ` Paul Durrant
2017-03-20 13:58 ` Jan Beulich
2017-03-17 9:57 ` [PATCH 3/7] x86/viridian: don't put Xen version information in CPUID leaf 2 Paul Durrant
2017-03-20 11:41 ` Jan Beulich
2017-03-20 11:57 ` Paul Durrant
2017-03-20 12:03 ` Jan Beulich
2017-03-20 13:08 ` Paul Durrant
2017-03-20 13:20 ` Jan Beulich
2017-03-17 9:57 ` [PATCH 4/7] x86/viridian: get rid of the magic numbers in CPUID leaves 1 and 2 Paul Durrant
2017-03-20 12:15 ` Jan Beulich
2017-03-20 12:56 ` Paul Durrant
2017-03-17 9:57 ` [PATCH 5/7] x86/viridian: add warnings for unimplemented hypercalls and MSRs Paul Durrant
2017-03-20 12:21 ` Jan Beulich
2017-03-20 12:54 ` Paul Durrant
2017-03-17 9:57 ` [PATCH 6/7] x86/viridian: make the threshold for HvNotifyLongSpinWait tunable Paul Durrant
2017-03-20 12:26 ` Jan Beulich
2017-03-20 12:51 ` Paul Durrant
2017-03-20 13:22 ` Jan Beulich
2017-03-20 17:03 ` Andrew Cooper
2017-03-20 17:07 ` Paul Durrant [this message]
2017-03-17 9:57 ` [PATCH 7/7] x86/viridian: implement the crash MSRs Paul Durrant
2017-03-20 12:38 ` Jan Beulich
2017-03-20 12:48 ` Paul Durrant
2017-03-20 13:29 ` Jan Beulich
2017-03-20 13:33 ` Paul Durrant
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