Hi,
My name is Rajiv Nishtala and I am a PhD student in UPC.
I am trying to investigate the performance (instructions per second
(IPS)) impact of an application on QEMU-KVM and bare metal using the
performance monitoring tools perfmon and perf. The performance counter
used for measuring this is "instructions" and "instructions_retired" on
perf and perfmon, respectively. The application is a *stress*
microbenchmark that does not produce any cache misses (LLC).
I account for the performance of the application on QEMU-KVM using the
following procedure:
A) Record the IPS of the QEMU-KVM (using its PID) on perf and perfmon
when idle.
B) Launch the stress benchmark and record IPS.
C) the difference between *B* and *A* should give the performance of the
application since the KVM does not inherently provide a technique to
collect this statistic.
However the performance of the application on bare metal is recorded as
is using the per-thread session available in perfmon and perf.
The sampling frequency to collect the statistics is 1 second.
The result obtained on bare metal are in the order of magnitude of
billions. On the other hand, results from KVM do not show any difference
in performance when idle or when an application is running and is in the
order of magnitude of 100's of thousands.
IPS_KVM_IDLE LLC_KVM_IDLE
IPS_KVM_STRESS LLC_KVM_STRESS
IPS_bare metal_STRESS LLC_bare metal_STRESS
47902 2495
25157 600
8116556011 3805
23437 758
48762 1032
8166564000 2140
834370 9954
543690 2379
8326333629 234
25261 662
49139 997
8057453733 1399
47998 2767
23773 600
8214761042 494
542039 2299
843266 2231
8075529487 4593
47982 2781
25249 603
8327678364 443
23833 794
49138 622
8058893864 1870
832913 9978
544567 2204
8210889659 394
I also tried using perf-kvm using the following command:
sudo perf kvm --guest --guestkallsyms=guest-kallsyms
--guestmodules=guest-modules record -a -o perf.data
but failed with the following error:
*Couldn't record guest kernel [0]'s reference relocation symbol.
*and no events were recorded.
I describe details of QEMU and the host machine (bare metal) below.
QEMU emulator version 2.0.0 in conjunction with KVM as the virtual
environment and libvirt 1.2.2
The guest machine is running kernel version 3.19.0-15-generic and the
host machine is running version 3.14.5-031405-generic on a x86_64 machine
I setup the guest machine with Intel SandyBridge processor (model
name:Intel Xeon E312xx) with the following flags:
sockets=2,cores=2,threads=1 and 4mb cache.
More details:
cpu family : 6
model : 42
max freq : 2394.560 MHz
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx rdtscp lm
constant_tsc rep_good nopl eagerfpu pni pclmulqdq vmx ssse3 cx16 pcid
sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx hypervisor
lahf_lm vnmi ept xsaveopt
The host machine is an Intel Sandy Bridge processor (Intel(R) Core(TM)
i7-2760QM CPU @ 2.40GHz) with 4 cores and 6mb cache.
cpu family : 6
model : 42
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall
nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology
nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx
smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt
tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts
dtherm tpr_shadow vnmi flexpriority ept vpid
Thanks
Rajiv Nishtala
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