On 11/26/2014 03:52 PM, Andi Kleen wrote:
> William Cohen <[email protected]> writes:
>
>> Hi,
>>
>> I have been looking at how perf supports cgroups and containers. The
>> "-G" option allows limiting the data collected to a particular cgroup.
>> Thus, one can use the option to collect some information about a
>> particular cgroup with something like:
>>
>> $ sudo perf stat -a -e cycles -G
>> machine.slice/machine-qemu\\x2drhel7\\x2dx86_64.scope -e instructions
>> -G machine.slice/machine-qemu\\x2drhel7\\x2dx86_64.scope -- sleep 1
>
> You can specify multiple events with -e. Typically you should anyways,
> to define appropiate groups with {}
>
> perf record -a -e cycles,instructions -G cgroup ...
>
> -Andi
>
Hi Andi,
Is there some where that explain use of the "{}" for event grouping? The
various perf man pages I have looked at (perf-record, perf-stat, and perf)
don't seem to mention it. When reading the following from "man perf-record" it
sounded like the comman separated event list wouldn't work:
-G name,..., --cgroup name,...
monitor only in the container (cgroup) called "name". This option
is available only in per-cpu mode. The cgroup filesystem must be
mounted. All threads belonging to container "name" are monitored
when they run on the monitored CPUs. Multiple cgroups can be
provided. Each cgroup is applied to the corresponding event, i.e.,
first cgroup to first event, second cgroup to second event and so
on. It is possible to provide an empty cgroup (monitor all the
time) using, e.g., -G foo,,bar. Cgroups must have corresponding
events, i.e., they always refer to events defined earlier on the
command line.
The results looks pretty questionable on my machine with the version of perf
and kernel I am using:
$ uname -a
Linux santana 3.17.3-200.fc20.x86_64 #1 SMP Fri Nov 14 19:45:42 UTC 2014 x86_64
x86_64 x86_64 GNU/Linux
$ rpm -q perf
perf-3.17.3-200.fc20.x86_64
$ sudo perf stat -a -e cycles,instructions -G
machine.slice/machine-qemu\\x2drhel7\\x2dx86_64.scope -- sleep .2
Performance counter stats for 'system wide':
2,983,776 cycles
machine.slice/machine-qemu\x2drhel7\x2dx86_64.scope [74.96%]
87,972,874 instructions # 29.48 insns per cycle
[100.00%]
0.201151985 seconds time elapsed
$ sudo perf stat -a -e "{cycles,instructions}" -G
machine.slice/machine-qemu\\x2drhel7\\x2dx86_64.scope -- sleep .2
Performance counter stats for 'system wide':
2,512,934 cycles
machine.slice/machine-qemu\x2drhel7\x2dx86_64.scope [82.53%]
813,334,082 instructions # 323.66 insns per cycle
[ 0.09%]
0.201360285 seconds time elapsed
-Will
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