* Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest
@ 2010-03-27 1:58 Naresh Rapolu
2010-03-27 4:38 ` Chris Wright
0 siblings, 1 reply; 4+ messages in thread
From: Naresh Rapolu @ 2010-03-27 1:58 UTC (permalink / raw)
To: kvm
Hello,
"perf" tool does not count hardware performance events ( cache misses
etc) in a KVM guest ( Ubuntu 9.10 karmic, 2.6.31-14-generic kernel)
on Xeon 5530 quad-core. The host is 2.6.28 kernel , Ubuntu 8.04
LTS, Hardy.
readfile.sh reads in a large file (1430 lines), which should cause
cache-misses.
root@multicore4-vm3:/usr/src/linux-2.6.31.12/tools/perf# ./perf stat -r
5 -- bash readfile.sh
Performance counter stats for 'bash readfile.sh' (5 runs):
11002.207467 task-clock-msecs # 1.042 CPUs ( +-
10.834% )
3480 context-switches # 0.000 M/sec (
+- 19.017% )
2238 CPU-migrations # 0.000 M/sec (
+- 29.488% )
482299 page-faults # 0.044 M/sec (
+- 0.141% )
0 cycles # 0.000
M/sec ( +- nan% )
0 instructions # nan
IPC ( +- nan% )
0 cache-references # 0.000 M/sec (
+- nan% )
0 cache-misses # 0.000 M/sec
( +- nan% )
10.560510393 seconds time elapsed ( +- 11.401% )
Do I need to make some configuration changes to enable hardware events
? A similar question was posted recently here :
http://lkml.org/lkml/2010/3/18/342 but no response !
Any help would be greatly appreciated.
Thanks,
Naresh Rapolu.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest
@ 2010-03-27 2:03 Naresh Rapolu
2010-03-28 11:57 ` Joerg Roedel
0 siblings, 1 reply; 4+ messages in thread
From: Naresh Rapolu @ 2010-03-27 2:03 UTC (permalink / raw)
To: linux-kernel
Hello,
"perf" tool does not count hardware performance events ( cache misses
etc) in a KVM guest ( Ubuntu 9.10 karmic, 2.6.31-14-generic kernel)
on Xeon 5530 quad-core. The host is 2.6.28 kernel , Ubuntu 8.04
LTS, Hardy.
readfile.sh reads in a large file (1430 lines), which should cause
cache-misses.
root@multicore4-vm3:/usr/src/linux-2.6.31.12/tools/perf# ./perf stat -r
5 -- bash readfile.sh
Performance counter stats for 'bash readfile.sh' (5 runs):
11002.207467 task-clock-msecs # 1.042 CPUs ( +-
10.834% )
3480 context-switches # 0.000 M/sec (
+- 19.017% )
2238 CPU-migrations # 0.000 M/sec (
+- 29.488% )
482299 page-faults # 0.044 M/sec (
+- 0.141% )
0 cycles # 0.000
M/sec ( +- nan% )
0 instructions # nan
IPC ( +- nan% )
0 cache-references # 0.000 M/sec (
+- nan% )
0 cache-misses # 0.000 M/sec (
+- nan% )
10.560510393 seconds time elapsed ( +- 11.401% )
Do I need to make some configuration changes to enable hardware events
? A similar question was posted recently here :
http://lkml.org/lkml/2010/3/18/342 but no response !
Any help would be greatly appreciated.
Thanks,
Naresh Rapolu.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest
2010-03-27 1:58 Naresh Rapolu
@ 2010-03-27 4:38 ` Chris Wright
0 siblings, 0 replies; 4+ messages in thread
From: Chris Wright @ 2010-03-27 4:38 UTC (permalink / raw)
To: Naresh Rapolu; +Cc: kvm
* Naresh Rapolu (nrapolu@purdue.edu) wrote:
> "perf" tool does not count hardware performance events ( cache misses
> etc) in a KVM guest
The guest does not see a PMU. For basic profiling you can use timer
based in guest, but there is not yet support for PMU.
thanks,
-chris
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest
2010-03-27 2:03 Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest Naresh Rapolu
@ 2010-03-28 11:57 ` Joerg Roedel
0 siblings, 0 replies; 4+ messages in thread
From: Joerg Roedel @ 2010-03-28 11:57 UTC (permalink / raw)
To: Naresh Rapolu; +Cc: linux-kernel
On Fri, Mar 26, 2010 at 10:03:10PM -0400, Naresh Rapolu wrote:
> "perf" tool does not count hardware performance events ( cache misses
> etc) in a KVM guest ( Ubuntu 9.10 karmic, 2.6.31-14-generic kernel)
> on Xeon 5530 quad-core. The host is 2.6.28 kernel , Ubuntu 8.04
> LTS, Hardy.
The KVM guest has no access to the hardware counters of the cpu. KVM
ignores these accesses from guests. Making this work needs proper
virtualization of the PMU which is not implemented yet.
Regards,
Joerg
^ permalink raw reply [flat|nested] 4+ messages in thread
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2010-03-27 2:03 Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest Naresh Rapolu
2010-03-28 11:57 ` Joerg Roedel
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2010-03-27 1:58 Naresh Rapolu
2010-03-27 4:38 ` Chris Wright
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