On Wed, Dec 23, 2009 at 10:53 AM, Avi Kivity <avi@xxxxxxxxxx> wrote: > On 12/23/2009 11:43 AM, Matthieu Olivier wrote: >> >> All, >> >> I am performing a study about KVM. >> (Shame on me, I did not check the version of kvm module. All I know is >> that I was using the last Red Hat EL 5.4. Anyway). >> >> I used a DELL server 2950, with: >> - 1 processor Xeon L5240 (3 Ghz, 6 Mo cache) >> - 8 GB of RAM >> - 4 disks SAS 15k in RAID-1 >> >> I created a procedure consist to launch a benchmark on several >> virtual machine at the same time. Each session consist in testing X VM, >> where X comes from 1 to 8. With nbench, I collected all results and >> extracted an average value of results for each VM. Then, I multiplied >> these average values by the number of VM in test, getting one unique >> and generic value per session of test. >> I did nearly the same with unixbench. >> >> On the host side, I launched the same tests, except that instead of >> running them in separate VM, I just launched several threads at the >> same time thanks to a script. >> >> My main purpose is watching the overhead due to these different >> hypervisors, according bechmark results. I am not really in trouble >> with KVM itself, but results of my benchmarks: >> >> -> http://img121.imageshack.us/img121/9279/nbench.png >> -> http://img704.imageshack.us/img704/953/unixbench.png >> >> Indeed, where I have all results growing from 1 VM tested to 8 VM, we >> can see the host growing from 1 to 8 VM. which seems good. But KVM >> only increases from 1 to 4 VM, and then stays on the same order of >> results, without growing anymore. >> The situation is inverse on Unixbench, where KVM seems to >> follow host's performances. >> > > What does 'top' show for nbench with 8 guests? How about kvm_stat? > > Are the results different for the 8 guests, or are they all making the same > progress? > > -- > error compiling committee.c: too many arguments to function To tell the truth, I had to test some others hypervisors, so now I don't have KVM installed anymore. I used top for following bench progress on 2 or 3 VM, but unfortunately I did not catch their output in a file, neither I used kvm_stat (by ignorance of its existence). But I still have every results of every tests of nbench and unixbench. >From 1 up to 4 VM, each VM have the same results. Indeed, it's because the Xeon L5240 is a quad core CPU (i forgot to mention that before). Over 4 tests, scores are still regulars, but decrease slowly as we add VMs. Here is the result of each VM, when I have tested 7 VM at the same time with nbench: -- VM 1: FOURIER 15637 NEURAL NET 30.58 LU DECOMPOSITION 985.18 -- VM 2: FOURIER 15512 NEURAL NET 30.443 LU DECOMPOSITION 1398.1 -- VM 3: FOURIER 15374 NEURAL NET 48.382 LU DECOMPOSITION 1954.6 -- VM 4: FOURIER 16159 NEURAL NET 37.007 LU DECOMPOSITION 1767.1 -- VM 5: FOURIER 15196 NEURAL NET 45.166 LU DECOMPOSITION 1981.1 -- VM 6: FOURIER 20948 NEURAL NET 60.256 LU DECOMPOSITION 1923.1 -- VM 7: FOURIER 15227 NEURAL NET 47.459 LU DECOMPOSITION 1972 According to nbench documentation, i recall that each test is run five times, and these five scores are averaged. So the output nbench shows us is already a average value. Unixbench did the same, i used an option to run each tests 4 times, in order to reduce exotic values. I'm not sure i have been clear about how I had my results, so tell me if you want I re-explain this point. -- Matthieu Olivier -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
