Bugs item #1998355, was opened at 2008-06-20 02:11
Message generated for change (Comment added) made by jessorensen
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Joshua Rosen (bjrosen)
Assigned to: Nobody/Anonymous (nobody)
Summary: IO Performance 

Initial Comment:
Is there any way of mapping a host's directory into a KVM VM similar to 
VMware's Shared Folder feature?

I've been benchmarking the performance of NCVerilog under various VMs. The 
performance of KVM when using a virtual disk is excellent, in fact it's better 
than VMware Server or VMware Workstation, however if you use
an NFS mounted host directory the performance is unspeakably awful. An NFS 
mounted directory under VMware Server 2.0 (Beta 2) is also slow but it's still 
significantly better than KVM. Using a Shared Folder with VMware Workstation 
eliminates the IO bottleneck, the performance there is about the same as 
accessing a virtual disk.

The system that I did these benchmarks on is a 3GHz Core2 with 8G of RAM. 
VMware was running under CentOS5.1 with a 2.6.23.7 kernel. KVM is running on 
Fedora 9 with a 2.6.25.xx kernel. The Verilog simulation times for my test 
suite are as follows,

Native                          06:34
VM Server 2, virtual disk       08:05
VM Server 2, NFS                18:37
VM Workstation, shared folder   08:14
KVM, Virtual disk               07:42
KVM, NFS                        38:36


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>Comment By: Jes Sorensen (jessorensen)
Date: 2010-08-19 12:18

Message:
Hi,

Did this get resolved? If so would you mind closing this bug. If I don't
hear back, I
will assume it is fixed and close it at some point :)

Thanks,
Jes


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Comment By: Joshua Rosen (bjrosen)
Date: 2008-06-22 15:54

Message:
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I've tried the following command line, it brings up the VM but I can't
configure the NIC, there is an error message about vlan 0.

qemu-kvm -M pc -m 512 -smp 1 -monitor pty -net
nic,macaddr=a0:1e:37:84:b1:da,model=virtio  -boot c -hda /home/xen/panther
Warning: vlan 0 is not connected to host network

I've also tried the following, but the qemu-ifup command is missing an
argument

qemu-kvm -M pc -m 512 -smp 1 -monitor pty -net
nic,macaddr=a0:1e:37:84:b1:da,model=virtio -net
tap,script=/etc/xen/qemu-ifup -boot c -hda /home/xen/panther
config qemu network with xen bridge for  tap0
Incorrect number of arguments for command
Usage: brctl addif <bridge> <device>    add interface to bridge
char device redirected to /dev/pts/3

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Comment By: Dor Laor (thekozmo)
Date: 2008-06-22 08:08

Message:
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Example cmdline:
./qemu/x86_64-softmmu/qemu-system-x86_64 -boot c -drive
file=/images/xpbase.qcow2,if=ide,cache=on,format=qcow2,boot=on -m 384  -net
nic,macaddr=a0:1e:37:84:b1:da,model=virtio -net
tap,script=/etc/kvm/qemu-ifup -snapshot

btw: you can use 'ps' to discover libvirt cmdline

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Comment By: Joshua Rosen (bjrosen)
Date: 2008-06-22 03:18

Message:
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How do I use virtio-net instead of virtio-blk?

I've been launching the VM using virt-manager which has no options. KVM
doesn't have a MAN page so I have no idea about how to launch the VM using
the CLI. Would you please give me specific step by step instructions.

Thanks,


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Comment By: Joshua Rosen (bjrosen)
Date: 2008-06-21 16:28

Message:
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How do I use virtio-net instead of virtio-blk?

I've been launching the VM using virt-manager which has no options. KVM
doesn't have a MAN page so I have no idea about how to launch the VM using
the CLI. Would you please give me specific step by step instructions.

Thanks,


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Comment By: Dor Laor (thekozmo)
Date: 2008-06-21 15:45

Message:
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If you don't boot from virtio-blk there is no need for this
configuration.
Just use virtio-net in order to boost nfs accesses.

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Comment By: Joshua Rosen (bjrosen)
Date: 2008-06-21 01:29

Message:
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The instructions for setting up virtio are a little confusing. I have a
CentOS5 VM on Fedora 9. F9 uses the 2.6.25 kernel. 

The wiki says to edit /etc/initramfs-tools/modules however it doesn't say
whether this file is on the host or the guest. There is no
/etc/initramfs-tools directory on either. Would someone please clarify the
procedure for adding a virtio NIC on an F9 host.


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Comment By: Dor Laor (thekozmo)
Date: 2008-06-20 23:58

Message:
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Did you use virtio nic when testing kvm with NFS?
If not, do try, it should boost your performance.

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