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Date: Wed, 13 Jun 2012 10:12:15 +0300
From: Gleb Natapov <gleb@redhat.com>
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Subject: Re: [Qemu-devel] Large sized guest taking for ever to boot...
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To: Chegu Vinod <chegu_vinod@hp.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, Alex Williamson <alex.williamson@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>

On Tue, Jun 12, 2012 at 11:44:07AM -0700, Chegu Vinod wrote:
> On 6/12/2012 8:39 AM, Gleb Natapov wrote:
> >On Tue, Jun 12, 2012 at 08:33:59AM -0700, Chegu Vinod wrote:
> >>I rebuilt the 3.4.1 kernel in the guest from scratch and retried my
> >>experiments and measured
> >>the boot times...
> >>
> >>a) Host :  RHEL6.3 RC1 + qemu-kvm (that came with it)&   Guest :
> >>RHEL6.3 RC1:  ~1 min
> >>
> >>b) Host :3.4.1 + qemu-kvm.git&  Guest : RHEL6.3RC1      -   ~1 min
> >>
> >>c) Host :3.4.1 + qemu-kvm.git&  Guest : 3.4.1      -   ~10 mins
> >>
> >>d) Host :3.4.1 + qemu.git&  Guest : RHEL6.3 RC1  -    ~1 min
> >>
> >>e) Host :3.4.1 + qemu.git&  Guest : 3.4.1                   -    ~14 mins
> >>
> >>
> >>In both the case (c)&  (e) had quite a few warning/error messages
> >>from udevd.
> >>
> >>FYI..
> >>Vinod
> >>PS:  Haven't had the time to do any further analysis...as the
> >>machine is being used for
> >>other experiments...
> >>
> >>
> >Next time you get the machine can you try running (b) but adding
> >-hypervisor to your -cpu config.
> 
> I tried that and didn't make any difference...i.e. the RHEL6.3 RC1
> guest booted in about ~1 min.
> 
Thank you. So this means that ticket spinlock is not to blame for the
slow down compared ti RHEL kernel.

Where 3.4.1 spends most of the time while booting? Is slow down begins
before or after the kernel starts userspace?

--
			Gleb.