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Re: [Qemu-devel] [Bug 992067] Re: Windows 2008R2 very slow cold boot whe

From: Alexandre DERUMIER
Subject: Re: [Qemu-devel] [Bug 992067] Re: Windows 2008R2 very slow cold boot when >4GB memory
Date: Tue, 01 May 2012 13:04:39 +0200 (CEST)

Hi, I was having this problem with qemu 0.15 ,  (win2008R2 x64 > 4GB).
guest with 32gb ram take around 40min to boot. (When windows fill memory at 
boot, memory grow slowly)

but now with last qemu kvm git (proxmox 2.0 distrib), it's working fine. (can 
tell for qemu 1.0)

----- Mail original -----

De: "Gleb Natapov" <address@hidden>
À: address@hidden
Cc: address@hidden, address@hidden
Envoyé: Mardi 1 Mai 2012 10:03:44
Objet: Re: [Qemu-devel] [Bug 992067] Re: Windows 2008R2 very slow cold boot 
when >4GB memory

On Mon, Apr 30, 2012 at 06:07:55PM -0000, Anthony Liguori wrote:
> This should be resolved by using Hyper-V relaxed timers which is in the
> latest development version of QEMU. You would need to add -cpu
> host,+hv_relaxed to the command line to verify this.
The described scenario still shouldn't happen and it doesn't for me.
Is this 32 or 64 bit version of Windows. Are you running 32 bit version
of the host may be (but Scientific Linux shouldn't have that)?
What is your command line?

> ** Changed in: qemu
> Status: New => Fix Committed
> --
> You received this bug notification because you are a member of qemu-
> devel-ml, which is subscribed to QEMU.
> https://bugs.launchpad.net/bugs/992067
> Title:
> Windows 2008R2 very slow cold boot when >4GB memory
> Status in QEMU:
> Fix Committed
> Bug description:
> I've been having a consistent problem booting 2008R2 guests with
> 4096MB of RAM or greater. On the initial boot the KVM process starts
> out with a ~200MB memory allocation and will use 100% of all CPU
> allocated to it. The RES memory of the KVM process slowly rises by
> around 200mb every few minutes until it reaches it's memory allocation
> (several hours in some cases). Whilst this is happening the guest will
> usually blue screen with the message of -
> A clock interrupt was not received on a secondary processor within the
> allocated time interval
> If I let the KVM process continue to run it will eventually allocate
> the required memory the guest will run at full speed, usually
> restarting after the blue screen and booting into startup repair. From
> here you can restart it and it will boot perfectly. Once booted the
> guest has no performance issues at all.
> I've tried everything I could think of. Removing PAE, playing with
> huge pages, different kernels, different userspaces, different
> systems, different backing file systems, different processor feature
> set, with or without Virtio etc. My best theory is that the problem is
> caused by Windows 2008 zeroing out all the memory on boot and
> something is causing this to be held up or slowed to a crawl. The
> hosts always have memory free to boot the guest and are not using swap
> at all.
> Nothing so far has solved the issue. A few observations I've made about the 
> issue are -
> Large memory 2008R2 guests seem to boot fine (or with a small delay) when 
> they are the first to boot on the host after a reboot
> Sometimes dropping the disk cache (echo 1 > /proc/sys/vm/drop_caches) will 
> cause them to boot faster
> The hosts I've tried are -
> All Nehalem based (5540, 5620 and 5660)
> Host ram of 48GB, 96GB and 192GB
> Storage on NFS, Gluster and local (ext4, xfs and zfs)
> QED, QCOW and RAW formats
> Scientific Linux 6.1 with the standard kernel 2.6.32, 2.6.38 and 3.3.1
> KVM userspaces 0.12, 0.14 and (currently) 0.15.1
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/992067/+subscriptions




        Alexandre D erumier
Ingénieur Système
Fixe : 03 20 68 88 90
Fax : 03 20 68 90 81
45 Bvd du Général Leclerc 59100 Roubaix - France
12 rue Marivaux 75002 Paris - France

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