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Re: [Qemu-devel] [PATCH] qemu:cpuid: speedup test by 3x times if grub2 i


From: Igor Mammedov
Subject: Re: [Qemu-devel] [PATCH] qemu:cpuid: speedup test by 3x times if grub2 is available
Date: Thu, 14 Feb 2013 20:28:03 +0100

On Thu, 14 Feb 2013 13:13:18 +0100
Paolo Bonzini <address@hidden> 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.
> 
> Paolo
I've tried Paolo's suggestion to run in TCG mode with instruction logging,
and it spends too much time reading 11K kernel from qemu compared to
kvm-unit-test kernel. I'll need debug it further to find out why.
But this patch looks unnecessary if I could fix qemu/seabios or test kernel
to reach the same load time as kvm-unit-test kernel.

-- 
Regards,
  Igor



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