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Re: [Qemu-devel] [RFC PATCH 3/4] pc: acpi: add _CST support
From: |
Igor Mammedov |
Subject: |
Re: [Qemu-devel] [RFC PATCH 3/4] pc: acpi: add _CST support |
Date: |
Wed, 15 Aug 2018 15:25:33 +0200 |
On Fri, 10 Aug 2018 02:01:00 +0300
"Michael S. Tsirkin" <address@hidden> wrote:
> On Thu, Aug 09, 2018 at 12:00:11PM +0200, Igor Mammedov wrote:
> > On Wed, 8 Aug 2018 23:17:48 +0300
> > "Michael S. Tsirkin" <address@hidden> wrote:
> >
> > > On Wed, Aug 08, 2018 at 05:15:48PM +0200, Igor Mammedov wrote:
> > > > Reuse CPU hotplug IO registers for passing a CST entry
> > > > containing package for shalowest C1 using mwait and
> > > > read it out in guest with new CCST AML method.
> > >
> > > I don't see how 1 entry is enough. We need to describe full _CST package
> > > so
> > > that guest can do reasonable power management on the CPU.
> > I was assuming that CST are to be used for mwait/monitor idle combo
> > to help reduce latencies/vmexits on cpus wakeup from idle state, hence 1
> > entry.
> > It's trivial to add as much as needed entries though.
> > If you are fine with approach I can respin patch with arbitrary
> > number of CStates.
>
> You will find that the code then becomes very messy, and
> dynamic size of the package is one of the things
> that makes it messy.
it turned up like extra ~10LOC, for a loop based impl.
I'll post amended patch here as reply with full update series in my repo.
>
> > > > The CState support is optional and could be turned on
> > > > with '-global PIIX4_PM.cstate=on' CLI option.
> > > >
> > > > Signed-off-by: Igor Mammedov <address@hidden>
> > > > ---
> > [...]
[Qemu-devel] [RFC PATCH 2/4] acpi: add aml_create_byte_field(), Igor Mammedov, 2018/08/08
[Qemu-devel] [RFC PATCH 4/4] acpi: add support for CST update notification, Igor Mammedov, 2018/08/08
Re: [Qemu-devel] [RFC PATCH 0/4] "pc: acpi: _CST support", Michael S. Tsirkin, 2018/08/08