XEN HVM storage I/O problem

alfikmik

alfikmik

I've got another problem (first of all I'd like to say it doesn't depends on kernel virtualization option). So better will be when I paste here some data from my performed experiences.

First of all the results for a real machine:

Code: 
CPU: Pentium(R) Dual-Core CPU E5700 @ 3.00GHz
real memory = 1063124992 (1013 MB)
atacontrol list
ad0 <ST3500413AS/JC45> Serial ATA II

Code: 
ioping -R -w 10 /dev/ad0s1

--- /dev/ad0s1 (device 74.5 GiB) ioping statistics ---
1.0 k requests completed in 10.0 s, 104 iops, 416.1 KiB/s
min/avg/max/mdev = 2.3 ms / 9.6 ms / 62.2 ms / 3.8 ms

Code: 
dd if=/dev/zero of=test bs=1k count=1M
1048576+0 records in
1048576+0 records out
1073741824 bytes transferred in 12.278704 secs (87447489 bytes/sec)

Code: 
ddpt if=/dev/zero of=test bs=1k count=1M conv=fdatasync
1048576+0 records in
1048576+0 records out
time to transfer data: 13.009085 secs at 82.54 MB/sec

Code: 
dd of=/dev/null if=test 
2097152+0 records in
2097152+0 records out
1073741824 bytes transferred in 12.070636 secs (88954867 bytes/sec)

Code: 
ddpt of=/dev/null if=test conv=fdatasync
Assume block size of 512 bytes for both input and output
2097152+0 records in
0+0 records out
time to read data: 11.705054 secs at 91.73 MB/sec

The second one is XEN HVM:

Code: 
ioping -R -w 10 /dev/ada0a 

--- /dev/ada0a (device 55.0 Gb) ioping statistics ---
153 requests completed in 10.1 s, 15 iops, 60.6 kb/s
min/avg/max/mdev = 522 us / 66.0 ms / 202.2 ms / 42.0 ms

Code: 
dd if=/dev/zero of=test bs=1k count=1M 
1048576+0 records in
1048576+0 records out
1073741824 bytes transferred in 4.793476 secs (224000674 bytes/sec)

Code: 
ddpt if=/dev/zero of=test bs=1k count=1M conv=fdatasync 
1048576+0 records in
1048576+0 records out
time to transfer data: 8.360690 secs at 128.43 MB/sec

Code: 
dd of=/dev/null if=test 
2097152+0 records in
2097152+0 records out
1073741824 bytes transferred in 4.487605 secs (239268353 bytes/sec)

Code: 
ddpt of=/dev/null if=test conv=fdatasync
Assume block size of 512 bytes for both input and output
2097152+0 records in
0+0 records out
time to read data: 3.903435 secs at 275.08 MB/sec

And the last one is KVM:

Code: 
ioping -R -w 10 /dev/vtbd0a 

--- /dev/vtbd0a (device 55.0 Gb) ioping statistics ---
1.2 k requests completed in 10.0 s, 123 iops, 493.4 kb/s
min/avg/max/mdev = 241 us / 8.1 ms / 91.5 ms / 5.5 ms

Code: 
dd if=/dev/zero of=test bs=1k count=1M 
1048576+0 records in
1048576+0 records out
1073741824 bytes transferred in 6.950562 secs (154482734 bytes/sec)

Code: 
ddpt if=/dev/zero of=test bs=1k count=1M conv=fdatasync 
1048576+0 records in
1048576+0 records out
time to transfer data: 10.699909 secs at 100.35 MB/sec

Code: 
dd of=/dev/null if=test 
2097152+0 records in
2097152+0 records out
1073741824 bytes transferred in 4.429863 secs (242387141 bytes/sec)

Code: 
ddpt of=/dev/null if=test conv=fdatasync
Assume block size of 512 bytes for both input and output
2097152+0 records in
0+0 records out
time to read data: 0.346330 secs at 3100.34 MB/sec

Both (XEN HVM and KVM) machines are in the same configuration: 2 cores 2,8GHz, 2GB RAM, 60GB HDD

I've tested both of them with and without kernel modules for virtualization. As you can see transfer rate for XEN HVM is pretty good but I/O operations are definitely too low for this one who wants to now for KVM better is if we enable kernel virtualization modules and for DomU disk driver is set to virtio.

I forgot mention that my tests was done with FreeBSD 9.0, 9.2 and 10.0, all amd64 (i386 sucks here); data pasted above are for FreeBSD 10.0 amd64.
 
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