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[Xen-users] Release 0.9.5 of GPL PV Drivers for Windows



James;

 

While educating myself in the fine art of Xen I have been lurking on the list and paying close attention to your incredible drivers.  I spent some time today doing exactly what you asked for, disk performance testing with and without your PV drivers, so I thought I would share my results with you and the list along with an interesting observation.  I hope you find this useful and have some ideas on what might be going wrong.  Also, I would like to contribute to Xen in general and this is an area where I feel I am able to offer some assistance. If there is anything in particular that you would like me to test in more detail or if you need any more information please let me know and I will do my best to make the time to work with you on this.  I have a rather large "Windows" estate running on various Hypervisors so I can probably come up with just about any configuration you want.  My current test configuration is as follows:

 

Dell Poweredge 1950, Dual 2.0 Ghz 5400 series Intel Procs , Perc 5i, 2 * SATA 750GB (RAID 1 - WB Cache Enabled in bios and Dom0), 16GB RAM.  All the BIOS' are one version out of date but there are no major bugs in any of it compelling me to update.

 

Xen 3.2.1 compiled from source

 

Dom0 is Centos 5.1

 

DomU's are on the local storage for testing purposes, an LVM root partition (default Centos Installation).  The only DomU's running on the machine are the ones mentioned here for these tests and tests were carried out on one DomU at a time.

 

All DomU's are fresh installations of:  Windows Server 2003, Standard, R2 SP2 <No windows updates>

 

I've attached the iometer configuration that I used.

Observation:

 

I have observed a possible incompatibility between QCOW image files and the PV drivers.  If I create a DomU with the above spec using an image file created using dd, for example:

 

dd if=/dev/zero of=guest_disk_sparse.img  bs=1k seek=8192k  count=1

 

Then the drivers work fine.

 

If I create the image file using:

 

qemu-img create -f qcow2 giest_disk_qcow.qcow 8G

 

I get a BSOD.. I can send you a pretty screen shot if you like.  And depending on my "disk" line in the HVM config I get the BSOD at different times.  Tap:aio bsods early in the boot and tap:qcow bsods quite late.

 

I double checked these results with two fresh machines, one running PV 0.9.1 and the other 0.9.5 just to be sure but it would be great if someone could double check my work?

 

Obviously I would prefer performance and stability over the functionality that the QCow disks give me but if this is an easy fix it would be great to have it all.

 

 

IOMETER Performance Results (see config attached)

 

 

Xen 3.2.1

No Tools

Xen 3.2.1

PV 0.95

Xen 3.2.1

PV 0.9.1

Xen 3.2.1

PV 0.9.5

Machine Name

Qcow1

Qcow

W2K3

RAW

Image Type

QCOW2

QCOW2

RAW

RAW

MAX IO's

 

 

 

 

Total I/O's per second

1801.43

BSOD

4385.78

16330.33

Total MBs per Second

0.88

2.14

7.97

Average I/O response Time

4.4096

1.8225

0.4890

MAX Throughput

 

 

 

 

Total I/O's per second

576.76

1446.27

547.64

Total MBs per Second

36.05

90.39

34.23

Average I/O response Time

13.8607

5.5269

14.5923

RealLife

 

 

 

 

Total I/O's per second

404.61

6763.00

610.42

Total MBs per Second

0.79

13.21

1.19

Average I/O response Time

19.7471

1.1815

13.0836

 

Best Regards

 

Geoff Wiener

 

Attachment: xenperformance.icf
Description: xenperformance.icf

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