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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: Wed, 25 Mar 2020 19:56:14 +0100
Message-ID: <20200325195614.41ecb022@redhat.com> (raw)
In-Reply-To: <20200325091636.rqqv3ewxue6wm5qe@sirius.home.kraxel.org>

On Wed, 25 Mar 2020 10:16:36 +0100
Gerd Hoffmann <kraxel@redhat.com> wrote:

> > > 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  
> 
> The kernel does a bunch of reads+writes at boot (roughly 20-30),
> mostly timer ports, so probably while initializing the pm_timer
> clocksource.  Then it stops talking to the acpi hardware,
> preferring kvmclock clocksouce I guess.
> 
> So I expect hw-reduced acpi wouldn't make much of a difference.
> Actually trying that isn't that high on my priority list.
> 
> There is bigger fish to fry, untangling the hw/i386/acpi-build.c
> monster for starters, so building with ACPI=y + PCI=n works ...

if you are after reducing start up time it may be better to leave alone
acpi-build.c with a bunch of legacy/compat stuff and create
microvm specific acpi file, and extract from acpi-build.c only common
bits that are necessary to produce tables (i.e. do something similar
hw/arm/virt-acpi-build.c)

PS:
side-note: guest kernel insist on finding PCI where it doesn't exists
[    0.301104] ACPI: bus type PCI registered
[    0.301717] acpiphp: ACPI Hot Plug PCI Controller Driver version: 0.5
[    0.302180] PCI: Fatal: No config space access function found

it's probably the first time x86 generic kernel sees machine without PCI,
and it probably could be fixed saving another 10-20ms


> 
> cheers,
>   Gerd
> 
> 



  parent 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
2020-03-25  9:16       ` Gerd Hoffmann
2020-03-25  9:53         ` Igor Mammedov
2020-03-25 18:56         ` Igor Mammedov [this message]
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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