From: Marcelo Tosatti <mtosatti@redhat.com>
To: Mark Petersen <mpetersen@peak6.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Shouta.Uehara@jp.yokogawa.com" <Shouta.Uehara@jp.yokogawa.com>
Subject: Re: Guest performance is reduced after live migration
Date: Wed, 2 Jan 2013 19:50:41 -0200 [thread overview]
Message-ID: <20130102215041.GA21706@amt.cnet> (raw)
In-Reply-To: <443D5D30774F8E4F8B2D304016C65D7A655AA85B@sswchi5pmbx1.peak6.net>
Can you describe more details of the test you are performing?
If transparent hugepages are being used then there is the possibility
that there has been no time for khugepaged to back guest memory
with huge pages, in the destination (don't recall the interface for
retrieving number of hugepages for a given process, probably somewhere
in /proc/pid/).
On Wed, Dec 19, 2012 at 12:43:37AM +0000, Mark Petersen wrote:
> Hello KVM,
>
> I'm seeing something similar to this (http://thread.gmane.org/gmane.comp.emulators.kvm.devel/100592) as well when doing live migrations on Ubuntu 12.04 (Host and Guest) with a backported libvirt 1.0 and qemu-kvm 1.2 (improved performance for live migrations on guests with large memory guests is great!) The default libvirt 0.9.8 and qemu-kvm 1.0 have the same issue.
>
> Kernel is 3.2.0-34-generic and eglicb 2.15 on both host/guest. I'm seeing similar issues with both virtio and ide bus. Hugetblfs is not used, but transparent hugepages are. Host machines are dual core Xeon E5-2660 processors. I tried disabling EPT but that doesn't seem to make a difference so I don't think it's a requirement to reproduce.
>
> If I use Ubuntu 10.04 guest with eglibc 2.11 and any of these kernels I don't seem to have the issue:
>
> linux-image-2.6.32-32-server - 2.6.32-32.62
> linux-image-2.6.32-38-server - 2.6.32-38.83
> linux-image-2.6.32-43-server - 2.6.32-43.97
> linux-image-2.6.35-32-server - 2.6.35-32.68~lucid1
> linux-image-2.6.38-16-server - 2.6.38-16.67~lucid1
> linux-image-3.0.0-26-server - 3.0.0-26.43~lucid1
> linux-image-3.2-5 - mainline 3.2.5 kernel
>
> I'm guess it's a libc issue (or at least a libc change causing the issue) as it doesn't seem to a be kernel related.
>
> I'll try other distributions as a guest (probably Debian/Ubuntu) with newer libc's and see if I can pinpoint the issue to a libc version. Any other ideas?
>
> Shared disk backend is clvm/LV via FC to EMC SAN, not sure what else might be relevant.
>
> Thanks,
> Mark
>
>
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>
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next prev parent reply other threads:[~2013-01-02 23:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-19 0:43 Guest performance is reduced after live migration Mark Petersen
2013-01-02 21:50 ` Marcelo Tosatti [this message]
2013-01-02 23:56 ` Mark Petersen
2013-01-03 0:48 ` Marcelo Tosatti
2013-01-03 1:32 ` Mark Petersen
2013-01-09 17:34 ` Mark Petersen
2013-01-17 0:05 ` Mark Petersen
-- strict thread matches above, loose matches on Subject: below --
2012-11-01 0:12 Shouta.Uehara
2012-11-01 4:45 ` Xiao Guangrong
2012-11-01 9:26 ` Shouta.Uehara
2012-11-09 9:51 ` Shouta.Uehara
[not found] ` <AF8F7CA61C57594089A6FF49A1B453A503EBDBD87D34@EXMAIL02.jp.ykgw.net>
2012-11-21 1:25 ` Shouta.Uehara
2012-11-21 3:31 ` Xiao Guangrong
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