trying to find the vm performance bottleneck

[srt4play]

Hi, I have proxmox 1.7 running on a ga-890fx-ud5 board with an Athlon II x4 and 6GB ddr3. I'm using iommu to successfully pass a pci-e tuner card to a windows7 vm whose only job is to run mediaportal tv server. This works great until I use the web interface to interact with any of my VMs, then the video and audio that are being served starts to break up. The windows vm is assigned 2 CPUs and 2GB RAM.

What first came to mind was a LAN speed issue, but Im running gigabit and the win7 vm has a dedicated nic. The nic is setup as e1000 and assigned as vmbr1, windows correctly sees the 1Gbps connection.

I also considered disk speed so assigned the windows vm its own dedicated hard disk. This helped a little but the problem remains. I was thinking a faster disk may cure it since mine are all 5400rpm. I wanted to get opinions before dropping money on a 10000rpm western digital raptor.

I am very new to virtualization. Any ideas on what the next troubleshooting steps should be?

 

[udo]

Hi, I have proxmox 1.7 running on a ga-890fx-ud5 board with an Athlon II x4 and 6GB ddr3. I'm using iommu to successfully pass a pci-e tuner card to a windows7 vm whose only job is to run mediaportal tv server. This works great until I use the web interface to interact with any of my VMs, then the video and audio that are being served starts to break up. The windows vm is assigned 2 CPUs and 2GB RAM.

What first came to mind was a LAN speed issue, but Im running gigabit and the win7 vm has a dedicated nic. The nic is setup as e1000 and assigned as vmbr1, windows correctly sees the 1Gbps connection.

I also considered disk speed so assigned the windows vm its own dedicated hard disk. This helped a little but the problem remains. I was thinking a faster disk may cure it since mine are all 5400rpm. I wanted to get opinions before dropping money on a 10000rpm western digital raptor.

I am very new to virtualization. Any ideas on what the next troubleshooting steps should be?

Hi,
you can use "pveperf" (e.g. "pveperf /var/lib/vz") to get performance values (as evidence).
I'm pretty sure that the disk-io is your problem. Especial with virtualisation is a good IO very helpfull.
The problem is here - for good io you need not only an raptor, better is an raidcontroller... with some raptors (raid-10). But i think this is oversized for your usecase.

Udo

 

[charlie0440]

I was looking at running a similar system. Could you tell me
which PCI-e DVB you are using?

also how hard was it to set up IOMMU I can't find any straightforward tutorials.

Sorry I cant help with your question

 

[srt4play]

Udo, thanks for the suggestion I will run pveperf later and show you the values for evaluation.

charlie, Im using an Avertv HD Duet. iommu was very easy to set up. Turn it on in the bios, find it's pci bus ID with lspci, add a line to the vm config file. There was a gotcha with the syntax of that line, I'll reply with that later today. Proxmox did not load a native driver for it so I did not need to blacklist any modules or de-assign the device from the host.

 

[srt4play]

Udo - pveperf results:

proxmox:~# pveperf /var/lib/vz
CPU BOGOMIPS: 24111.27
REGEX/SECOND: 1034024
HD SIZE: 354.61 GB (/dev/mapper/pve-data)
BUFFERED READS: 88.26 MB/sec
AVERAGE SEEK TIME: 12.57 ms
FSYNCS/SECOND: 776.91
DNS EXT: 48.50 ms
DNS INT: 35.04 ms (local)

and on the disk that holds the win7 image:
proxmox:~# pveperf /var/lib/vz1
CPU BOGOMIPS: 24111.27
REGEX/SECOND: 988375
HD SIZE: 458.45 GB (/dev/sdf1)
BUFFERED READS: 76.07 MB/sec
AVERAGE SEEK TIME: 13.05 ms
FSYNCS/SECOND: 631.89
DNS EXT: 52.82 ms
DNS INT: 33.65 ms (local)

These are 500GB 5400rpm Western Digital green drives. Do you think a couple raptors in mdadm RAID0 would make a difference?

charlie - The line I added to the vm config file is:

args: -device pci-assign,host=04:00.0

The gotcha was that the command syntax I kept finding was -pcidevice host=04:00.0 (that didn't work) until I found the above syntax at this link:

http://web.archiveorange.com/archive/v/1XS1vjengNzyhkCXc4iI

 

[udo]

Udo - pveperf results:

proxmox:~# pveperf /var/lib/vz
CPU BOGOMIPS: 24111.27
REGEX/SECOND: 1034024
HD SIZE: 354.61 GB (/dev/mapper/pve-data)
BUFFERED READS: 88.26 MB/sec
AVERAGE SEEK TIME: 12.57 ms
FSYNCS/SECOND: 776.91
DNS EXT: 48.50 ms
DNS INT: 35.04 ms (local)

and on the disk that holds the win7 image:
proxmox:~# pveperf /var/lib/vz1
CPU BOGOMIPS: 24111.27
REGEX/SECOND: 988375
HD SIZE: 458.45 GB (/dev/sdf1)
BUFFERED READS: 76.07 MB/sec
AVERAGE SEEK TIME: 13.05 ms
FSYNCS/SECOND: 631.89
DNS EXT: 52.82 ms
DNS INT: 33.65 ms (local)

These are 500GB 5400rpm Western Digital green drives. Do you think a couple raptors in mdadm RAID0 would make a difference?

charlie - The line I added to the vm config file is:

args: -device pci-assign,host=04:00.0

The gotcha was that the command syntax I kept finding was -pcidevice host=04:00.0 (that didn't work) until I found the above syntax at this link:

http://web.archiveorange.com/archive/v/1XS1vjengNzyhkCXc4iI

Hi,
I had no experience with softraid under proxmox (is not supported, but some people used it).
Your performance are ok for non-raid. But you get better read-rates with other disks.

Try to look with "top" if you see what happens during the problem. Are there more wait (IO)?
To eliminate network-bottleneck, you can for testing create an internal bridge and stream the video to another VM over the internal bridge (with virtio).

Udo