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    SubjectRe: [PATCH 02/25] perf stat record: Add record command
    Em Thu, Nov 05, 2015 at 03:40:46PM +0100, Jiri Olsa escreveu:
    > Add 'perf stat record' command support. It creates simple
    > (header only) perf.data file ATM.
    >
    > The record command could be specified anywhere among stat
    > options. All stat command options are valid for stat record
    > command with '-o' option exception. If specified for record
    > command it denotes the perf data file name.
    >
    > Tested-by: Kan Liang <kan.liang@intel.com>
    > Link: http://lkml.kernel.org/n/tip-0av5yfkwyywwgoiali88w4hi@git.kernel.org
    > Signed-off-by: Jiri Olsa <jolsa@kernel.org>

    Still stopping here:

    [acme@zoo linux]$ rm -f perf.data
    [acme@zoo linux]$ perf stat record usleep 1

    Performance counter stats for 'usleep 1':

    0.621181 task-clock (msec) # 0.455 CPUs utilized
    1 context-switches # 0.002 M/sec
    0 cpu-migrations # 0.000 K/sec
    54 page-faults # 0.087 M/sec
    917,006 cycles # 1.476 GHz
    611,746 stalled-cycles-frontend # 66.71% frontend cycles idle
    <not supported> stalled-cycles-backend
    654,410 instructions # 0.71 insns per cycle
    # 0.93 stalled cycles per insn
    132,653 branches # 213.550 M/sec
    7,432 branch-misses # 5.60% of all branches

    0.001365369 seconds time elapsed

    [acme@zoo linux]$ ls -la perf.data
    -rw-------. 1 acme acme 1384 Nov 5 17:42 perf.data
    [acme@zoo linux]$ perf evlist
    WARNING: The perf.data file's data size field is 0 which is unexpected.
    Was the 'perf record' command properly terminated?
    non matching sample_type[acme@zoo linux]$

    --------------------------------

    When we pass one event it gets a bit better:

    [acme@zoo linux]$ rm -f perf.data
    [acme@zoo linux]$ perf stat -e cycles record usleep 1

    Performance counter stats for 'usleep 1':

    1,056,818 cycles

    0.000715850 seconds time elapsed

    [acme@zoo linux]$ ls -la perf.data
    -rw-------. 1 acme acme 232 Nov 5 17:44 perf.data
    [acme@zoo linux]$ perf evlist
    WARNING: The perf.data file's data size field is 0 which is unexpected.
    Was the 'perf record' command properly terminated?
    cycles
    [acme@zoo linux]$

    -----

    In the second case it almost works, modulo that warning.

    I think that what we need to achieve is for older tools to be able to, with a
    file produced by 'perf stat record', to show this:

    [root@zoo ~]# perf report --no-header --stdio
    Error:
    The perf.data file has no samples!
    # To display the perf.data header info, please use --header/--header-only options.
    #
    [root@zoo ~]#


    I.e. the file should look like one that is produced by this command, purposely
    to not create any sample:

    # perf record -e syscalls:sys_enter_accept usleep 1
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.018 MB perf.data ]


    I applied the first patch and added it to that perf/stat branch.

    - Arnaldo


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