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From: Igor Mammedov <imammedo@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
	Sergio Lopez <slp@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH 00/13] microvm: add acpi support
Date: Mon, 23 Mar 2020 13:16:58 +0100
Message-ID: <20200323131658.30152128@redhat.com> (raw)
In-Reply-To: <20200323120948.f6egd7rhfso6276p@sirius.home.kraxel.org>

On Mon, 23 Mar 2020 13:09:48 +0100
Gerd Hoffmann <kraxel@redhat.com> wrote:

> On Mon, Mar 23, 2020 at 06:51:10AM -0400, Michael S. Tsirkin wrote:
> > On Thu, Mar 19, 2020 at 09:01:04AM +0100, Gerd Hoffmann wrote:  
> > > I know that not supporting ACPI in microvm is intentional.  If you still
> > > don't want ACPI this is perfectly fine, you can use the usual -no-acpi
> > > switch to toggle ACPI support.
> > > 
> > > These are the advantages you are going to loose then:
> > > 
> > >   (1) virtio-mmio device discovery without command line hacks (tweaking
> > >       the command line is a problem when not using direct kernel boot).
> > >   (2) Better IO-APIC support, we can use IRQ lines 16-23.
> > >   (3) ACPI power button (aka powerdown request) works.
> > >   (4) machine poweroff (aka S5 state) works.  
> > 
> > What is the cost though? How do boot times compare?  
> 
> Well, acpi speeds up booting by one second because this delay ...
> 
>    [    0.275736] i8042: PNP: No PS/2 controller found.
>    [    0.275736] i8042: Probing ports directly.
>    [    1.315447] i8042: No controller found
> 
> ... goes away, at least with standard distro kernels.  When building
> your own you can probably compile out the driver somehow, even though
> something seems to select SERIO_I8042 so trying to simply flip
> CONFIG_SERIO_I8042 to 'n' in .config doesn't work.  And a runtime
> switch seems to not be there either ...
> 
> So that ruined my plan to just time until the root filesystem is
> mounted.  Decided to use the "i8042: PNP: No PS/2 controller found."
> line instead for a simple test (just check the kernel log timestamps,
> three runs each).  The ACPI initialization is already done at that
> point, so it should be useful nevertheless.  Here we go:
> 
> Without acpi:
>   0.277710
>   0.278852
>   0.279520
> 
> With acpi:
>   0.283917
>   0.284262
>   0.284836
I wonder what would be difference with hw-reduced acpi

> So the difference is less than 0.01 seconds on my box.
> 
> cheers,
>   Gerd
> 



  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-19  8:01 Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 01/13] acpi: make build_madt() more generic Gerd Hoffmann
2020-03-19  9:34   ` Philippe Mathieu-Daudé
2020-03-19  8:01 ` [PATCH 02/13] acpi: factor out acpi_dsdt_add_fw_cfg() Gerd Hoffmann
2020-03-19  9:36   ` Philippe Mathieu-Daudé
2020-03-19 12:16   ` Igor Mammedov
2020-03-19  8:01 ` [PATCH 03/13] microvm: add isa-acpi device Gerd Hoffmann
2020-03-19 13:42   ` Igor Mammedov
2020-03-20  8:22     ` Gerd Hoffmann
2020-03-20 14:54       ` Igor Mammedov
2020-03-19  8:01 ` [PATCH 04/13] microvm: add minimal acpi support Gerd Hoffmann
2020-03-19 14:00   ` Igor Mammedov
2020-03-25  9:04     ` Gerd Hoffmann
2020-03-25 18:59       ` Igor Mammedov
2020-03-19  8:01 ` [PATCH 05/13] microvm: add acpi_dsdt_add_virtio() for x86 Gerd Hoffmann
2020-03-19 14:30   ` Igor Mammedov
2020-03-20  8:19     ` Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 06/13] microvm: disable virtio-mmio cmdline hack Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 07/13] [testing] seabios: update submodule to experimental microvm branch Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 08/13] [testing] seabios: update config & build rules Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 09/13] [testing] seabios: update binaries to experimental microvm branch Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 10/13] microvm/acpi: add rtc Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 11/13] microvm/acpi: add serial Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 12/13] microvm: make virtio irq base runtime configurable Gerd Hoffmann
2020-03-19  8:01 ` [PATCH 13/13] microvm/acpi: use GSI 16-23 for virtio Gerd Hoffmann
2020-03-20 15:30   ` Konrad Rzeszutek Wilk
2020-03-23 10:23     ` Gerd Hoffmann
2020-03-19  8:19 ` [PATCH 00/13] microvm: add acpi support no-reply
2020-03-19  8:23 ` no-reply
2020-03-19  8:24 ` no-reply
2020-03-19  8:49 ` Paolo Bonzini
2020-03-19  9:33   ` Gerd Hoffmann
2020-03-19  9:59     ` Paolo Bonzini
2020-03-19 11:28       ` Gerd Hoffmann
2020-03-19 13:40   ` Gerd Hoffmann
2020-03-19 17:34     ` Paolo Bonzini
2020-03-20  8:32       ` Gerd Hoffmann
2020-03-20 10:41         ` Paolo Bonzini
2020-03-23 10:51 ` Michael S. Tsirkin
2020-03-23 12:09   ` Gerd Hoffmann
2020-03-23 12:16     ` Igor Mammedov [this message]
2020-03-25  9:16       ` Gerd Hoffmann
2020-03-25  9:53         ` Igor Mammedov
2020-03-25 18:56         ` Igor Mammedov
2020-03-25 12:32 ` Igor Mammedov
2020-03-25 15:03   ` Gerd Hoffmann
2020-03-25 18:44     ` Igor Mammedov
2020-03-26  7:33       ` Michael S. Tsirkin
2020-03-26 10:59         ` Igor Mammedov
2020-03-27 12:06       ` Gerd Hoffmann
2020-03-27 14:05         ` Igor Mammedov

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