From: "René Pfeiffer" <lynx@luchs.at>
To: kvm@vger.kernel.org
Subject: I/O performance of VirtIO
Date: Mon, 12 Oct 2009 22:49:03 +0200 [thread overview]
Message-ID: <20091012204901.GA10688@nightfall.luchs.at> (raw)
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Hello!
I just tested qemu-kvm-0.11.0 with the KVM module of kernel 2.6.31.1. I
noticed that the I/O performance of an unattended stock Debian Lenny
install dropped somehow. The test machines ran with kvm-88 and 2.6.30.x
before. The difference is very noticeable (went from about 5 minutes up
to 15-25 minutes). The two test machines have different CPUs (one is an
Intel Core2 CPU, the other runs with an AMD Athlon 64 X2 Dual).
Is this the effect of added code regarding caching/data integrity to the
VirtIO block layer or somewhere else? The qemu-system-x86_64 seems to
hang a lot more in heavy I/O (showing 'D' in top/htop).
The command line is quite straight-forward:
qemu-system-x86_64 -drive file=debian.qcow2,if=virtio,boot=on -cdrom \
/srv/isos/debian-502-i386-netinst.iso -smp 2 -boot d -m 512 -net nic \
-net user -usb
Installation was repeated multiple times, every time the test machines
hat no other load. The effect is the same with a Windows XP guest
running without VirtIO.
Best,
René.
--
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next reply other threads:[~2009-10-12 21:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-12 20:49 René Pfeiffer [this message]
2009-10-12 21:45 ` I/O performance of VirtIO Michael Tokarev
2009-10-12 21:54 ` René Pfeiffer
2009-10-13 6:35 ` Jan Kiszka
2009-10-22 16:29 ` Avi Kivity
2009-10-22 22:06 ` Alexander Graf
2009-10-25 5:44 ` Avi Kivity
2009-10-26 8:12 ` Jan Kiszka
2009-10-26 8:35 ` Avi Kivity
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