Messages in this thread | | | From | Cong Wang <> | Date | Thu, 24 May 2018 15:23:28 -0700 | Subject | Re: [PATCH 3/3] sched/fair: add tracepoints for cfs throttle |
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On Thu, May 24, 2018 at 12:11 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > The problem with tracepoints is that they can become ABI and you cannot > change them without breaking tools. This is a crap situation and I'm fed > up with it.
Yeah, I once used perf_event_open() to parse the trace events, I understand how painful it is. Fortunately tools like bcc mostly hides the ABI from end user. To be fair, kprobe has the same problem if not worse, different compilers could inline different kernel functions, not to mention kernel functions could change at any time.
OTOH, the tracepoint text interface is sufficient to help people to inspect kernel internals, like in this case I can observe when a cpu cgroup is throttled or unthrottled. Of course they are not friendly for programming.
Thanks.
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