On Wed, Feb 22, 2017 at 09:22:25AM -0800, Stefano Stabellini wrote:
> On Wed, 22 Feb 2017, Edgar E. Iglesias wrote:
> > On Tue, Feb 21, 2017 at 07:20:29PM +, Julien Grall wrote:
> > >
> > >
> > > On 21/02/2017 18:30, Stefano Stabellini wrote:
> > > >On Tue, 21 Feb 2017, Julien Grall wrote:
>
On Wed, 22 Feb 2017, Edgar E. Iglesias wrote:
> On Tue, Feb 21, 2017 at 07:20:29PM +, Julien Grall wrote:
> >
> >
> > On 21/02/2017 18:30, Stefano Stabellini wrote:
> > >On Tue, 21 Feb 2017, Julien Grall wrote:
> > >>Hi Stefano,
> > >>
> > >>On 21/02/17 17:49, Stefano Stabellini wrote:
> > >>
On Tue, 2017-02-21 at 18:17 +, George Dunlap wrote:
> On 21/02/17 17:49, Stefano Stabellini wrote:
> > I don't know the inner working of the scheduler, but does it always
> > send
> > an interrupt to other pcpu to schedule something?
>
> Letting a guest call WFI is as safe as letting a guest
>
On Tue, Feb 21, 2017 at 07:20:29PM +, Julien Grall wrote:
>
>
> On 21/02/2017 18:30, Stefano Stabellini wrote:
> >On Tue, 21 Feb 2017, Julien Grall wrote:
> >>Hi Stefano,
> >>
> >>On 21/02/17 17:49, Stefano Stabellini wrote:
> >>>On Tue, 21 Feb 2017, Dario Faggioli wrote:
> On Tue, 2017-0
On 21/02/2017 18:30, Stefano Stabellini wrote:
On Tue, 21 Feb 2017, Julien Grall wrote:
Hi Stefano,
On 21/02/17 17:49, Stefano Stabellini wrote:
On Tue, 21 Feb 2017, Dario Faggioli wrote:
On Tue, 2017-02-21 at 13:46 +, George Dunlap wrote:
Oh, actually, if --which I only now realize may
On Tue, 21 Feb 2017, Julien Grall wrote:
> Hi Stefano,
>
> On 21/02/17 17:49, Stefano Stabellini wrote:
> > On Tue, 21 Feb 2017, Dario Faggioli wrote:
> > > On Tue, 2017-02-21 at 13:46 +, George Dunlap wrote:
> > > Oh, actually, if --which I only now realize may be what you are
> > > referring
Hi Stefano,
On 21/02/17 18:03, Stefano Stabellini wrote:
On Tue, 21 Feb 2017, Julien Grall wrote:
Hi George,
On 21/02/17 13:46, George Dunlap wrote:
I think our options look like:
Thank you for the summary of the options!
A. Don't trap guest WFI at all -- allow it to 'halt' in
moderate-
On 21/02/17 17:49, Stefano Stabellini wrote:
> On Tue, 21 Feb 2017, Dario Faggioli wrote:
>> On Tue, 2017-02-21 at 13:46 +, George Dunlap wrote:
>>>
>>> A. Don't trap guest WFI at all -- allow it to 'halt' in
>>> moderate-power-but-ready-for-interrupt mode.
>>>
>>> [..]
>>>
>>> A is safe becau
On Tue, 21 Feb 2017, Julien Grall wrote:
> Hi George,
>
> On 21/02/17 13:46, George Dunlap wrote:
> > I think our options look like:
>
> Thank you for the summary of the options!
>
> >
> > A. Don't trap guest WFI at all -- allow it to 'halt' in
> > moderate-power-but-ready-for-interrupt mode.
Hi Stefano,
On 21/02/17 17:49, Stefano Stabellini wrote:
On Tue, 21 Feb 2017, Dario Faggioli wrote:
On Tue, 2017-02-21 at 13:46 +, George Dunlap wrote:
Oh, actually, if --which I only now realize may be what you are
referring to, since you're talking about "guest burning its credits"--
you
On Tue, 21 Feb 2017, Dario Faggioli wrote:
> On Tue, 2017-02-21 at 13:46 +, George Dunlap wrote:
> >
> > A. Don't trap guest WFI at all -- allow it to 'halt' in
> > moderate-power-but-ready-for-interrupt mode.
> >
> > [..]
> >
> > A is safe because the scheduler should already have set a time
On Tue, 21 Feb 2017, Dario Faggioli wrote:
> On Tue, 2017-02-21 at 12:30 +, Julien Grall wrote:
> > On 21/02/2017 09:09, Dario Faggioli wrote:
> > > Well, TBH, we still are not entirely sure who the culprit is for
> > > high
> > > latency. There are spikes in Credit2, and I'm investigating that
On 21/02/17 15:14, Julien Grall wrote:
> Hi George,
>
> On 21/02/17 13:46, George Dunlap wrote:
>> I think our options look like:
>
> Thank you for the summary of the options!
>
>>
>> A. Don't trap guest WFI at all -- allow it to 'halt' in
>> moderate-power-but-ready-for-interrupt mode.
>>
>> B
On Tue, 2017-02-21 at 12:30 +, Julien Grall wrote:
> On 21/02/2017 09:09, Dario Faggioli wrote:
> > Well, TBH, we still are not entirely sure who the culprit is for
> > high
> > latency. There are spikes in Credit2, and I'm investigating that.
> > But
> > apart from them? I think we need other
Hi George,
On 21/02/17 13:46, George Dunlap wrote:
I think our options look like:
Thank you for the summary of the options!
A. Don't trap guest WFI at all -- allow it to 'halt' in
moderate-power-but-ready-for-interrupt mode.
B. Trap guest WFI and block normally.
C. Trap guest WFI and pol
On Tue, 2017-02-21 at 13:46 +, George Dunlap wrote:
>
> A. Don't trap guest WFI at all -- allow it to 'halt' in
> moderate-power-but-ready-for-interrupt mode.
>
> [..]
>
> A is safe because the scheduler should already have set a timer to
> break
> out of it if necessary. The only potential
On 21/02/17 12:30, Julien Grall wrote:
> Hi Dario,
>
> On 21/02/2017 09:09, Dario Faggioli wrote:
>> On Tue, 2017-02-21 at 07:59 +, Julien Grall wrote:
>>> On 20/02/2017 22:53, Dario Faggioli wrote:
For instance, as you say, executing a WFI from a guest directly on
hardware, only mak
Hi Dario,
On 21/02/17 09:24, Dario Faggioli wrote:
On Tue, 2017-02-21 at 08:10 +, Julien Grall wrote:
On 21/02/2017 00:38, Stefano Stabellini wrote:
On Mon, 20 Feb 2017, Dario Faggioli wrote:
Mmm... ok, yes, in that case, it may make sense and work, from a,
let's
say, purely functional pe
Hi Dario,
On 21/02/2017 09:09, Dario Faggioli wrote:
On Tue, 2017-02-21 at 07:59 +, Julien Grall wrote:
On 20/02/2017 22:53, Dario Faggioli wrote:
For instance, as you say, executing a WFI from a guest directly on
hardware, only makes sense if we have 1:1 static pinning. Which
means
it can
On Tue, 2017-02-21 at 08:10 +, Julien Grall wrote:
> On 21/02/2017 00:38, Stefano Stabellini wrote:
> > On Mon, 20 Feb 2017, Dario Faggioli wrote:
> > > Mmm... ok, yes, in that case, it may make sense and work, from a,
> > > let's
> > > say, purely functional perspective. But still I struggle t
On Tue, 2017-02-21 at 07:59 +, Julien Grall wrote:
> On 20/02/2017 22:53, Dario Faggioli wrote:
> > For instance, as you say, executing a WFI from a guest directly on
> > hardware, only makes sense if we have 1:1 static pinning. Which
> > means
> > it can't just be done by default, or with a bo
Hi Stefano,
On 21/02/2017 00:38, Stefano Stabellini wrote:
On Mon, 20 Feb 2017, Dario Faggioli wrote:
On Mon, 2017-02-20 at 19:38 +, Julien Grall wrote:
On 20/02/17 19:20, Dario Faggioli wrote:
E.g., if vCPU x of domain A wants to go idle with a WFI/WFE, but
the
host is overbooked and cur
Hi Dario,
On 20/02/2017 22:53, Dario Faggioli wrote:
On Mon, 2017-02-20 at 19:38 +, Julien Grall wrote:
On 20/02/17 19:20, Dario Faggioli wrote:
E.g., if vCPU x of domain A wants to go idle with a WFI/WFE, but
the
host is overbooked and currently really busy, Xen wants to run some
other vC
On Mon, 20 Feb 2017, Dario Faggioli wrote:
> On Mon, 2017-02-20 at 19:38 +, Julien Grall wrote:
> > On 20/02/17 19:20, Dario Faggioli wrote:
> > > E.g., if vCPU x of domain A wants to go idle with a WFI/WFE, but
> > > the
> > > host is overbooked and currently really busy, Xen wants to run some
On Mon, 2017-02-20 at 19:38 +, Julien Grall wrote:
> On 20/02/17 19:20, Dario Faggioli wrote:
> > E.g., if vCPU x of domain A wants to go idle with a WFI/WFE, but
> > the
> > host is overbooked and currently really busy, Xen wants to run some
> > other vCPU (of either the same of another domain
Hi Dario,
On 20/02/17 19:20, Dario Faggioli wrote:
On Mon, 2017-02-20 at 18:53 +, Julien Grall wrote:
On 20/02/17 18:47, Stefano Stabellini wrote:
This is a good question, I have already answered: I think it would
break
the scheduler. Dario confirmed it in his reply
(1487382463.6732.146.ca
On Mon, 2017-02-20 at 18:53 +, Julien Grall wrote:
> On 20/02/17 18:47, Stefano Stabellini wrote:
> > This is a good question, I have already answered: I think it would
> > break
> > the scheduler. Dario confirmed it in his reply
> > (1487382463.6732.146.ca...@citrix.com).
>
> I don't think it
Hi Stefano,
On 20/02/17 18:47, Stefano Stabellini wrote:
On Sun, 19 Feb 2017, Julien Grall wrote:
I don't think this is acceptable even to get a better interrupt latency.
Some
workload will care about interrupt latency and power.
I think a better approach would be to check whether the schedule
On Mon, 20 Feb 2017, George Dunlap wrote:
> On 20/02/17 18:43, Stefano Stabellini wrote:
> > On Mon, 20 Feb 2017, Dario Faggioli wrote:
> >> On Sun, 2017-02-19 at 21:34 +, Julien Grall wrote:
> >>> Hi Stefano,
> >>>
> >>> I have CCed another ARM person who has more knowledge than me on
> >>> s
On Sun, 19 Feb 2017, Julien Grall wrote:
> Hi Stefano,
>
> I have CCed another ARM person who has more knowledge than me on
> scheduling/power.
>
> On 02/17/2017 10:50 PM, Stefano Stabellini wrote:
> > CC'ing xen-devel, I forgot on the original patch
> >
> > On Fri, 17 Feb 2017, Julien Grall wro
On 20/02/17 18:43, Stefano Stabellini wrote:
> On Mon, 20 Feb 2017, Dario Faggioli wrote:
>> On Sun, 2017-02-19 at 21:34 +, Julien Grall wrote:
>>> Hi Stefano,
>>>
>>> I have CCed another ARM person who has more knowledge than me on
>>> scheduling/power.
>>>
>> Ah, when I saw this, I thought y
On Mon, 20 Feb 2017, Dario Faggioli wrote:
> On Sun, 2017-02-19 at 21:34 +, Julien Grall wrote:
> > Hi Stefano,
> >
> > I have CCed another ARM person who has more knowledge than me on
> > scheduling/power.
> >
> Ah, when I saw this, I thought you were Cc-ing my friend Juri, which
> also work
On Sun, 2017-02-19 at 21:34 +, Julien Grall wrote:
> Hi Stefano,
>
> I have CCed another ARM person who has more knowledge than me on
> scheduling/power.
>
Ah, when I saw this, I thought you were Cc-ing my friend Juri, which
also works there, and is doing that stuff. :-)
> > In both cases th
On Sun, 2017-02-19 at 21:27 +, Julien Grall wrote:
> Hi Dario,
>
Hi,
> On 02/18/2017 01:47 AM, Dario Faggioli wrote:
> > - vcpu A yields, and there are no runnable but not running vcpus
> > around. In this case, A gets to run again. Full stop.
>
> Which turn to be the busy looping I was
On 19/02/17 21:27, Julien Grall wrote:
> Hi Dario,
>
> On 02/18/2017 01:47 AM, Dario Faggioli wrote:
>> On Fri, 2017-02-17 at 14:50 -0800, Stefano Stabellini wrote:
>>> On Fri, 17 Feb 2017, Julien Grall wrote:
Please explain in which context this will be beneficial. My gut
feeling is
>>>
Hi Stefano,
I have CCed another ARM person who has more knowledge than me on
scheduling/power.
On 02/17/2017 10:50 PM, Stefano Stabellini wrote:
CC'ing xen-devel, I forgot on the original patch
On Fri, 17 Feb 2017, Julien Grall wrote:
Hi Stefano,
On 02/16/2017 11:04 PM, Stefano Stabellini
Hi Dario,
On 02/18/2017 01:47 AM, Dario Faggioli wrote:
On Fri, 2017-02-17 at 14:50 -0800, Stefano Stabellini wrote:
On Fri, 17 Feb 2017, Julien Grall wrote:
Please explain in which context this will be beneficial. My gut
feeling is
only will make performance worst if a multiple vCPU of the sa
On Fri, 2017-02-17 at 14:50 -0800, Stefano Stabellini wrote:
> On Fri, 17 Feb 2017, Julien Grall wrote:
> > Please explain in which context this will be beneficial. My gut
> > feeling is
> > only will make performance worst if a multiple vCPU of the same
> > guest is
> > running on vCPU
>
> I am n
CC'ing xen-devel, I forgot on the original patch
On Fri, 17 Feb 2017, Julien Grall wrote:
> Hi Stefano,
>
> On 02/16/2017 11:04 PM, Stefano Stabellini wrote:
> > Introduce new Xen command line parameter called "vwfi", which stands for
> > virtual wfi. The default is "sleep": on guest wfi, Xen cal
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