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    SubjectRe: [PATCH 1/1] perf,tools: add time out to force stop endless mmap processing
    On 6/12/15 12:19 PM, Liang, Kan wrote:
    >>> [perf]$ sudo ./perf record -e instructions:pp --pid 14560 Reading
    >>> /proc/14560/maps cost 13.12690599 s ^C[ perf record: Woken up 1 times
    >>> to write data ] [ perf record: Captured and wrote 0.108 MB perf.data
    >>> (2783 samples) ]
    >>
    >> so perf was able to read the proc file?
    >
    > Yes, perf always can read proc file. The problem is that the proc file is
    > huge and keep growing faster than proc reader.
    > So perf top do loop in perf_event__synthesize_mmap_events until the
    > test case exit.

    I'm confused. How are you getting the above time to read /proc maps if
    it never finishes?


    >> Are you sure task_diag is enabled? There is an option under General I
    >> believe:
    >> config TASK_DIAG
    >> bool "Export task/process properties through netlink"
    >> depends on NET && TASKSTATS
    >> default n
    >> help
    >> Export selected properties for tasks/processes through the
    >> generic netlink interface. Unlike the proc file system, task_diag
    >> returns information in a binary format, allows to specify which
    >> information are required.
    >>
    >> Say N if unsure.
    >>
    > It works now.

    for this test case how does perf-record compare between proc and
    task_diag? You can use my command for both. It defaults to using
    task_diag and then you can add --no-task_diag to have it read /proc. And
    as mentioned before it is only setup for 'perf record -a' case. So

    launch your test program
    perf record -a -- usleep 1
    perf record -a --no-task_diag -- usleep 1




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