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One can set a cgroup as a default cgroup to be used by all events or
set cgroups with the 'perf stat' and 'perf record' behaviour, i.e.
'-G A' will be the cgroup for events defined so far in the command line.
Here in my main machine, with a kvm instance running a rhel6 guinea pig
I have:
# ls -la /sys/fs/cgroup/perf_event/ | grep drw
drwxr-xr-x. 14 root root 360 Mar 6 12:04 ..
drwxr-xr-x. 3 root root 0 Mar 6 15:05 machine.slice
#
So I can go ahead and use that cgroup hierarchy, say lets see what
syscalls are being emitted by threads in that 'machine.slice' hierarchy
that are taking more than 100ms:
# perf trace --duration 100 -G machine.slice
0.188 (249.850 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
250.274 (249.743 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
500.224 (249.755 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
750.097 (249.934 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
1000.244 (249.780 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
1250.197 (249.796 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
1500.124 (249.859 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
1750.076 (172.900 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
902.570 (1021.116 ms): qemu-system-x8/23667 ppoll(ufds: 0x558151e03180, nfds: 74, tsp: 0x7ffc00cd0900, sigsetsize: 8) = 1
1923.825 (305.133 ms): qemu-system-x8/23667 ppoll(ufds: 0x558151e03180, nfds: 74, tsp: 0x7ffc00cd0900, sigsetsize: 8) = 1
2000.172 (229.002 ms): CPU 0/KVM/23744 ioctl(fd: 16<anon_inode:kvm-vcpu:0>, cmd: KVM_RUN) = 0
^C #
If we look inside that cgroup hierarchy we get:
# ls -la /sys/fs/cgroup/perf_event/machine.slice/ | grep drw
drwxr-xr-x. 3 root root 0 Mar 6 15:05 .
drwxr-xr-x. 2 root root 0 Mar 6 16:16 machine-qemu\x2d2\x2drhel6.sandy.scope
#
There is just one, but lets say there were more and we would want to see
5 seconds worth of syscall summary for the threads in that cgroup:
# perf trace --summary -G machine.slice/machine-qemu\\x2d2\\x2drhel6.sandy.scope/ -a sleep 5
Summary of events:
qemu-system-x86 (23667), 143858 events, 24.2%
syscall calls total min avg max stddev
(msec) (msec) (msec) (msec) (%)
--------------- -------- --------- --------- --------- --------- ------
ppoll 28492 4348.631 0.000 0.153 11.616 1.05%
futex 19661 140.801 0.001 0.007 2.993 3.20%
read 18440 68.084 0.001 0.004 1.653 4.33%
ioctl 5387 24.768 0.002 0.005 0.134 1.62%
CPU 0/KVM (23744), 449455 events, 75.8%
syscall calls total min avg max stddev
(msec) (msec) (msec) (msec) (%)
--------------- -------- --------- --------- --------- --------- ------
ioctl 148364 3401.812 0.000 0.023 11.801 1.15%
futex 36131 404.127 0.001 0.011 7.377 2.63%
writev 29452 339.688 0.003 0.012 1.740 1.36%
write 11315 45.992 0.001 0.004 0.105 1.10%
#
See the documentation about how to set more than one cgroup for
different events in the same command line.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-t126jh4occqvu0xdqlcjygex@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.