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    SubjectRe: [PATCH 3/3] perf callchain: Prune misleading callchains for self entries
    On Thu, Aug 14, 2014 at 03:01:40PM +0900, Namhyung Kim wrote:

    SNIP

    > However, with --children feature added, it now can show all callees of
    > the entry. For example, "start_kernel" entry now can display it calls
    > rest_init and in turn cpu_idle and then cpuidle_idle_call (95.72%).
    >
    > 6.14% 0.00% swapper [kernel.kallsyms] [k] start_kernel
    > |
    > --- start_kernel
    > rest_init
    > cpu_idle
    > |
    > |--97.52%-- cpuidle_idle_call
    > | cpuidle_enter_tk
    > | |
    > | |--99.91%-- cpuidle_wrap_enter
    > | | cpuidle_enter
    > | | intel_idle
    > | --0.09%-- [...]
    > --2.48%-- [...]
    >
    > Note that start_kernel has no self overhead - meaning that it never
    > get sampled by itself but constructs such a nice callgraph. But,
    > sadly, if an entry has self overhead, callchain will get confused with
    > generated callchain (like above) and self callchains (which reversed
    > order) like the eariler example.
    >
    > To be consistent with other entries, I'd like to make it just to show
    > a single entry - itself - like below since it doesn't have callees
    > (children) at all. But still use the whole callchain to construct
    > children entries (like the start_kernel) as usual.
    >
    > 40.53% 40.53% swapper [kernel.kallsyms] [k] intel_idle
    > |
    > --- intel_idle

    I understand the consistency point, but I think we'd loose
    usefull info by cutting this off

    I guess I can run 'report -g callee' to find out who called intel_idle
    instead.. but I would not need to if the callchain stays here

    jirka


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