Hi All,
I'm finding this results a bit surprising , could some please explain whether this is the expected behavior.
I'm running a single threaded application ( calculating pi for many decimal points ). Each VM has 1 vcpu with 128MB of ram. The physical box has quad-core processor ( HT disabled ). When I increase the number of VMs the time it takes to calculate the result
taking longer ( Performance goes down ). I could clearly see that each VM will just use 1 CPU when it is running the tests.
Why there is a such a huge jump in time although there are enough physical cores available ( at least upto 3 Vms) ?
Please let me know if any more information is necessary.
VM1 – 31.85
Number of VMs.
VM1 – 35.98
VM2 – 36.11
Number of Vms
VM1 - 43.57
VM2 - 42.55
VM3 -42.48
Number of VMs
VM1 - 51.093
VM2 - 49.953
VM3 - 50.141
VM3 - 49.844
XEN version
dpkg -l | grep -i xen
ii libc6-xen 2.11.2-6 Embedded GNU C Library: Shared libraries [Xen version]
ii libxenstore3.0 4.0.1-1 Xenstore communications library for Xen
ii linux-image-2.6.32-5-xen-686 2.6.32-23 Linux 2.6.32 for modern PCs, Xen dom0 support
ii xen-hypervisor-4.0-amd64 4.0.1-1 The Xen Hypervisor on AMD64
ii xen-tools 4.2-1 Tools to manage Xen virtual servers
ii xen-utils-4.0 4.0.1-1 XEN administrative tools
ii xen-utils-common 4.0.0-1 XEN administrative tools - common files
ii xenstore-utils 4.0.1-1 Xenstore utilities for Xen
All guest machines 'uname -a'
Linux vm1 2.6.32-5-xen-686 #1 SMP Thu Aug 12 18:09:47 UTC 2010 i686 GNU/Linux
xm dmesg| grep -i credit
(XEN) Using scheduler: SMP Credit Scheduler (credit)
xm sched-credit
Name ID Weight Cap
Domain-0 0 256 0
vm1 57 256 100
vm2 58 256 100
Dom0 is pinned to CPU0.
Name ID VCPU CPU State Time(s) CPU Affinity
Domain-0 0 0 0 r-- 6907.9 0
Domain-0 0 1 - --p 74.9 any cpu
Domain-0 0 2 - --p 92.4 any cpu
Domain-0 0 3 - --p 62.2 any cpu
vm1 57 0 2 -b- 6614.7 any cpu
vm2 58 0 1 -b- 5797.1 any cpu
--
Dkar
