SIGs/PowerManagementBaseOS/Testcase Virtualized 32bit vs 64bit

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The main aim of this test was comparison of syscall count, tick count, read/written bytes when performing the same task on virtual 32-bit and 64-bit machine.

Contents

System configuration

We used VirtualBox OSE and KVM to perform this test. All virtual machines run on the same physical machine (not simultaneously) in the same configuration.

  • The host configuration:
    • Intel Core 2 Duo E8400 3GHz
    • 4 GB of memory
    • Fedora 11 (2.6.30.5-43.fc11.x86_64)
    • VirtualBox 3.0.4_OSE r50677
    • libvirt 0.6.2-17.fc11, qemu 2:0.10.6-4.fc11
  • The guest configuration in VirtualBox:
    • 1 CPU (32bit or 64bit)
    • 1024 MB of memory
    • ACPI: enabled, PAE/NX: enabled, VT-x: enabled, Nested paging: enabled
    • Fedora Rawhide (2009-09-16), i686 or x86_64
    • VirtualBox Guest Additions
  • The guest configuration in KVM
    • 1 CPU (i686 or x86_64)
    • 1024 MB or memory
    • Fedora Rawhide (2009-09-16), i686 or x86_64
    • virtio disk
Note.png
Virtual disks conversion
The tests were run on VirtualBox machines at first. After that, the virtual disks were converted to QEMU format (qcow2) and used in KVM - to have the same installation.
Important.png
Guest Additions for VirtualBox
Absence of Guest Additions has great influence on guest system performance especially when running 64-bit guest. If you are going to verify this test or create similar, don't forget to install Guest Additions before.

Test description

The results were measured using scomes (SystemTap script) which can be found in tuned-utils package. However we used the newest GIT version [1].

The test run 10 times in sequence. Clean caches, dentries and inodes were dropped before each run:

echo 3 > /proc/sys/vm/drop_caches

The measured task was building squid RPM package from src.rpm:

./scomes.stp -c "rpmbuild --rebuild squid-3.1.0.13-3.fc12.src.rpm" 0

Uprocessed results

VirtualBox 32-bit guest

syscalls kernel ticks userspace ticks read bytes written bytes
1 176379 9169 5860 19815353 19496541
2 175957 9410 6057 19434866 19502130
3 175336 9341 5553 18696381 19489876
4 175072 9063 5522 18815017 19495984
5 175316 9186 5542 18788471 19495878
6 176232 9033 5353 19460705 19501778
7 174503 8979 5621 18517294 19489876
8 188483 21269 4921 31460765 20263640
9 189830 9248 5811 32850019 20232887
10 175268 19736 4881 18657208 19492557

VirtualBox 64-bit guest

syscalls kernel ticks userspace ticks read bytes written bytes
1 175694 14905 8232 21770053 19564938
2 177300 14098 8037 19354317 19529482
3 179318 15268 7757 20555112 19549143
4 177070 9890 4724 18915315 19523128
5 177867 9826 4824 19321045 19529497
6 177306 10282 4792 18802447 19523195
7 178227 10220 4823 19181444 19531070
8 178271 9927 4855 19824862 19540823
9 178032 10149 4833 19304156 19529428
10 177906 10395 4798 19360721 19529566

KVM 32-bit guest

syscalls kernel ticks userspace ticks read bytes written bytes
1 174540 8151 2571 19280444 19486683
2 174399 7673 2181 18968357 19495090
3 186836 7546 2224 30935608 20265990
4 174674 7487 2218 19028456 19494972
5 174393 7456 2193 18782550 19490383
6 174520 7380 2213 18857743 19487497
7 186927 7637 2216 30870324 20263823
8 174531 7415 2235 18720100 19490277
9 171019 7261 2073 15000148 19468860
10 187081 7662 2256 30930304 20265406

KVM 64-bit guest

syscalls kernel ticks userspace ticks read bytes written bytes
1 173268 8092 1959 19782678 19532133
2 179307 8181 1979 19696304 19535759
3 179870 8234 1980 20019461 19549543
4 178176 8674 2130 19169793 19529757
5 176884 7736 2087 18466457 19518977
6 177183 6532 1975 18316321 19521145
7 177831 6413 1985 18794279 19521145
8 177022 6346 1864 18241975 19519216
9 177116 6447 1920 18445540 19523166
10 177891 6342 1905 18695531 19523532

Results

syscalls count

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 178237.6 177699.1 177892 177454.8 -0.30% -0.25%
median 175646.5 177886.5 174535.5 177507 1.28% 1.70%
min 174503 175694 171019 173268 0.68% 1.32%
max 189830 179318 187081 179870 -5.54% -3.85%

Testcase Virtualized 32bit vs 64bit Graph Syscalls.png

ticks count

kernel

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 11443.4 11496 7566.8 7299.7 0.46% -3.53%
median 9217 10251 7516.5 7134 11.22% -5.09%
min 8979 9826 7261 6342 9.43% -12.66%
max 21269 15268 8151 8674 -28.21% 6.42%

Testcase Virtualized 32bit vs 64bit Graph Kernel Ticks.png

userspace

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 5512.1 5767.5 5512.1 1978.4 4.63% -64.11%
median 5547.5 4828.5 5547.5 1977 -12.96% -64.36%
min 4881 4724 4881 1864 -3.22% -61.81%
max 6057 8232 6057 2130 35.91% -64.83%

Testcase Virtualized 32bit vs 64bit Graph Userspace Ticks.png

total

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 16955.5 17263.5 13078.9 9278.1 1.82% -29.06%
median 14961.5 15058.5 13040.5 9165 0.65% -29.72%
min 14386 14614 12336 8210 1.58% -33.45%
max 26190 23137 14011 10804 -11.66% -22.89%

Testcase Virtualized 32bit vs 64bit Graph Total Ticks.png

read/written bytes

read

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 21649607.9 19638947.2 22137403.4 18962833.9 -9.29% -14.34%
median 19124941.5 19337681 18998406.5 18744905 1.11% -1.33%
min 18517294 18802447 15000148 18241975 1.54% 21,61%
max 32850019 21770053 30935608 20019461 -33.73% -35.29%

Testcase Virtualized 32bit vs 64bit Graph Data Read.png

written

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 19646114.7 19535027 19720898.1 19527437.3 -0.57% -0.98%
median 19496262.5 19529531.5 19492677.5 19523349 0.17% 0.16%
min 19489876 19523128 19468860 19518977 0.17% 0.26%
max 20263640 19564938 20265990 19549543 -3.45% -3.54%

Testcase Virtualized 32bit vs 64bit Graph Data Written.png

total

VBox 32bit VBox 64bit KVM 32bit KVM 64bit VBox 32→64 increase KVM 32→64 increase
average 41295722.6 39173974.2 41858301.5 38490271.2 -5.14% -8.05%
median 38623998.5 38867170.5 38493437.5 38267243.5 0.63% -0.59%
min 38007170 38325642 34469008 37761191 0.84% 9.55%
max 53082906 41334991 51201598 39569004 -22.13% -22.72%

Testcase Virtualized 32bit vs 64bit Graph Data Total.png

Conclusion

According to the graphs the most stable results are provided by KVM 64-bit.

If we consider the average results to be predicative, it seems that there is almost no difference in syscall count between the architectures and virtualization tools.

As for the ticks: The 64-bit system under VirtualBox produced totally a bit more ticks than 32-bit system (mostly in userspace). In KVM the difference is much bigger, 64-bit system needs a bit more kernel ticks but far fewer user ticks, which makes totally approximately 30% ticks less than 32-bit system.

The difference in read/written bytes on both virtualization tools is not wide (as we expected). There is only i difference between 32-bit and 64-bit system. It seems that the second one is a bit better in read byte count.