• Arnaldo Carvalho de Melo's avatar
    perf trace: Support setting cgroups as targets · 9ea42ba4
    Arnaldo Carvalho de Melo authored
    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.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    9ea42ba4
perf-trace.txt 7.45 KB