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Re: [Qemu-devel] [PATCH] qemu:cpuid: speedup test by 3x times if grub2 i
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From: |
Eduardo Habkost |
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Subject: |
Re: [Qemu-devel] [PATCH] qemu:cpuid: speedup test by 3x times if grub2 is available |
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Date: |
Thu, 14 Feb 2013 11:24:08 -0200 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Feb 14, 2013 at 01:13:18PM +0100, Paolo Bonzini wrote:
> Il 14/02/2013 12:18, Eduardo Habkost ha scritto:
> >> > qemu boots from disk image 3 times faster than direct kernel load.
> > That's surprising. Do you have any idea why that happens?
>
> Because kernel load uses MMIO (from fw_cfg), while booting from disk
> uses at worst PCI DMA and at best virtio.
Is it something worth trying to optimize, or a reasonable solution would
be so similar to having a disk+bootloader that's easier to simply
recommend people to set up a real disk with a real bootloader if they
care about speed?
--
Eduardo
Re: [Qemu-devel] [PATCH] qemu:cpuid: speedup test by 3x times if grub2 is available, Igor Mammedov, 2013/02/14