John has a little server that he's installed Debian on + KVM. We're trying to get the VMs to run well. The goal is to use the machine as a teaching platform using the Windows VMs as clean base images for which to run testing software.
Right now the disk I/O on this server is a little lack-luster. It may be the disk itself. Maybe we can tune things?
Here's an idea: https://serverfault.com/questions/407842/incredibly-low-kvm-disk-performance-qcow2-disk-files-virtio
First let's test the host disk I/O. I've run apt-get install lshw to inspect
the type of disk. lsscsi says that sda is an ST3250312AS. It's 7200 RPM SATA 6Gb/s with NCQ. Let's run an actual throughput test. The first dd test showed 68.1 MB/s which is 544 Mb/s.
The hdparm read tests showed:
ryan@debianTaradi00:~$ sudo hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 26224 MB in 1.98 seconds = 13227.32 MB/sec
Timing buffered disk reads: 366 MB in 3.01 seconds = 121.44 MB/sec
ryan@debianTaradi00:~$ sudo hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 26194 MB in 1.98 seconds = 13211.55 MB/sec
Timing buffered disk reads: 364 MB in 3.00 seconds = 121.33 MB/sec
It seems low. According to a benchmarking site, we're in the ballpark.
Now let's move on to KVM guest performance. We need a way to measure Windows 10 I/O performance first. DiskSpd feels promising. Ok first run is:
Here's the first run:
C:\Users\john\Desktop\amd64>diskspd -b4K -t2 -r -o32 -d10 -Sh testfile.dat
Command Line: diskspd -b4K -t2 -r -o32 -d10 -Sh testfile.dat
Input parameters:
timespan: 1
-------------
duration: 10s
warm up time: 5s
cool down time: 0s
random seed: 0
path: 'testfile.dat'
think time: 0ms
burst size: 0
software cache disabled
hardware write cache disabled, writethrough on
performing read test
block size: 4096
using random I/O (alignment: 4096)
number of outstanding I/O operations: 32
thread stride size: 0
threads per file: 2
using I/O Completion Ports
IO priority: normal
System information:
computer name: DESKTOP-SJ5N5IK
start time: 2019/12/10 20:53:15 UTC
Results for timespan 1:
*******************************************************************************
actual test time: 10.02s
thread count: 2
proc count: 2
CPU | Usage | User | Kernel | Idle
-------------------------------------------
0| 97.66%| 6.40%| 91.26%| 2.34%
1| 97.82%| 0.16%| 97.66%| 2.18%
-------------------------------------------
avg.| 97.74%| 3.28%| 94.46%| 2.26%
Total IO
thread | bytes | I/Os | MiB/s | I/O per s | file
------------------------------------------------------------------------------
0 | 300134400 | 73275 | 28.58 | 7316.26 | testfile.dat (8192KiB)
1 | 61763584 | 15079 | 5.88 | 1505.59 | testfile.dat (8192KiB)
------------------------------------------------------------------------------
total: 361897984 | 88354 | 34.46 | 8821.85
Read IO
thread | bytes | I/Os | MiB/s | I/O per s | file
------------------------------------------------------------------------------
0 | 300134400 | 73275 | 28.58 | 7316.26 | testfile.dat (8192KiB)
1 | 61763584 | 15079 | 5.88 | 1505.59 | testfile.dat (8192KiB)
------------------------------------------------------------------------------
total: 361897984 | 88354 | 34.46 | 8821.85
Write IO
thread | bytes | I/Os | MiB/s | I/O per s | file
------------------------------------------------------------------------------
0 | 0 | 0 | 0.00 | 0.00 | testfile.dat (8192KiB)
1 | 0 | 0 | 0.00 | 0.00 | testfile.dat (8192KiB)
------------------------------------------------------------------------------
total: 0 | 0 | 0.00 | 0.00
Ok, so now I'm installing the virtio Windows drivers. I've mounted the iso and install the qemu guest agent, viostor and vioscsi. After rebooting, Windows won't boot. Let's try this workaround. Didn't work. Maybe I need to install all the virtio drivers. Adding a new virtio drive and then switching the boot drive over worked.
Now let's rerun the test above. Wow!
C:\Users\john\Desktop\amd64>diskspd.exe -b4K -t2 -r -o32 -d10 -Sh testfile.dat
Command Line: diskspd.exe -b4K -t2 -r -o32 -d10 -Sh testfile.dat
Input parameters:
timespan: 1
-------------
duration: 10s
warm up time: 5s
cool down time: 0s
random seed: 0
path: 'testfile.dat'
think time: 0ms
burst size: 0
software cache disabled
hardware write cache disabled, writethrough on
performing read test
block size: 4096
using random I/O (alignment: 4096)
number of outstanding I/O operations: 32
thread stride size: 0
threads per file: 2
using I/O Completion Ports
IO priority: normal
System information:
computer name: DESKTOP-SJ5N5IK
start time: 2019/12/10 21:38:08 UTC
Results for timespan 1:
*******************************************************************************
actual test time: 10.02s
thread count: 2
proc count: 2
CPU | Usage | User | Kernel | Idle
-------------------------------------------
0| 100.00%| 4.68%| 95.32%| 0.00%
1| 100.00%| 3.12%| 96.88%| 0.00%
-------------------------------------------
avg.| 100.00%| 3.90%| 96.10%| 0.00%
Total IO
thread | bytes | I/Os | MiB/s | I/O per s | file
------------------------------------------------------------------------------
0 | 699727872 | 170832 | 66.63 | 17056.26 | testfile.dat (8192KiB)
1 | 851058688 | 207778 | 81.04 | 20745.03 | testfile.dat (8192KiB)
------------------------------------------------------------------------------
total: 1550786560 | 378610 | 147.66 | 37801.29
Read IO
thread | bytes | I/Os | MiB/s | I/O per s | file
------------------------------------------------------------------------------
0 | 699727872 | 170832 | 66.63 | 17056.26 | testfile.dat (8192KiB)
1 | 851058688 | 207778 | 81.04 | 20745.03 | testfile.dat (8192KiB)
------------------------------------------------------------------------------
total: 1550786560 | 378610 | 147.66 | 37801.29
Write IO
thread | bytes | I/Os | MiB/s | I/O per s | file
------------------------------------------------------------------------------
0 | 0 | 0 | 0.00 | 0.00 | testfile.dat (8192KiB)
1 | 0 | 0 | 0.00 | 0.00 | testfile.dat (8192KiB)
------------------------------------------------------------------------------
total: 0 | 0 | 0.00 | 0.00
That's about 3.5X the performance.
Now let's install the spice guest tools for video performance. Oh, that spice guest tools installer installs all the virtio stuff too. We should just do that from now on. Ok so I also had to [add a spice channel] to get the auto resizing working.