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    SubjectRe: [RFC PATCH 0/4] perf: Custom contexts
    On Mon, Mar 14, 2011 at 06:03:15PM -0300, Arnaldo Carvalho de Melo wrote:
    > Em Mon, Mar 14, 2011 at 09:51:02PM +0100, Frederic Weisbecker escreveu:
    > > On Mon, Mar 14, 2011 at 05:43:41PM -0300, Arnaldo Carvalho de Melo wrote:
    > > > > - Count instructions inside softirqs, outside softirqs and everywhere:
    >
    > > > > $ perf stat -e irq:softirq_entry -e irq:softirq_exit \
    > > > > -e instructions --starter 0 --stopper 1 --enable-on-starter \
    > > > > -e instructions --starter 1 --stopper 0 \
    > > > > -e instructions ./perf bench sched messaging
    >
    > > > $ perf record -e instructions@irq:softirq_entry..irq:softirq_exit \
    > > > -e instructions@irq:softirq_exit..irq:softirq_entry \
    > > > -e instructions \
    > > > perf bench sched messaging
    >
    > > Agreed that's nice but may be more as a shortcut than a full replacement?
    > > Otherwise it becomes hard or unreadable to define a filter on a starter. Or
    > > a starter on a starter.
    >
    > Sure, multiple ways to express ranges probably is ok, with more complex
    > ones for more complex cases, like the way you did, that first defines an
    > evlist that is the set of starters/stoppers and then evsel->evidx to add
    > starters/stoppers to later events.

    Yep.

    > But starter on a starter? Couldn't grok, could you provide an example?

    I have no strong example in mind.

    But one may want to count instructions when we are in an interrupt and
    lock A is held.

    Or count instruction when A and B are held. Or count instruction in
    page faults happening in read() syscall.

    Event range define a state, and anytime you need to profile/trace a
    desired stacked state, starters on starters can be a good solution,
    thus even a common practice.

    > But I could think of this as a way to express filters:
    >
    > $ perf record -e instructions@irq:irq:irq_handler_entry(irq=eth0)..irq:irq_handler_exit(\1) \
    > -e instructions \
    > netperf
    >
    > looks quite natural for someone used to git and sed, i.e. developers :)

    Yeah indeed, I like filters defined in parenthesis after the event!


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