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    SubjectRe: [RFC][PATCH 3/9] perf: export registerred pmus via sysfs
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    On Tue, 2010-05-11 at 17:12 +0800, Peter Zijlstra wrote:
    > On Tue, 2010-05-11 at 17:03 +0800, Lin Ming wrote:
    > > On Tue, 2010-05-11 at 16:50 +0800, Peter Zijlstra wrote:
    > > > On Tue, 2010-05-11 at 16:20 +0800, Lin Ming wrote:
    > > >
    > > > > How will this sysfs interface be used for userspace tool?
    > > > >
    > > > > /sys/devices/system/node/nodeN/node_events
    > > > > node_events/event_source_id
    > > > >
    > > > > node_events/local_misses/event_id
    > > > > /local_hits/event_id
    > > > > /remote_misses/event_id
    > > > > /remote_hits/event_id
    > > > >
    > > > > For example, to monitor node event local_misses on node 0, does it work
    > > > > as below?
    > > > >
    > > > > 1. perf top -e local_misses -n 0 (-n 0 means node 0)
    > > > >
    > > > > 2. read /sys/devices/system/node/node0/node_events/event_source_id to
    > > > > get the pmu_id
    > > > >
    > > > > 3. read /sys/devices/system/node/node0/node_events/local_misses/event_id
    > > > > to get the event_id
    > > > >
    > > > > 4. event_attr::pmu_id=pmu_id, event::config=event_id
    > > > >
    > > > > 5. other setting...
    > > > >
    > > > > 6. call syscall perf_event_open(....)
    > > >
    > > > No, you'll use event_source_id as perf_event_attr::type, use event_id as
    > > > perf_event_attr::config and then use a cpu-wide counter on a cpu
    > > > contained in node0.
    > >
    > > Is event_source_id a link to event_source class?
    >
    > No its an attribute of said class.
    >
    > > For example, 2 event sources on Nehalem
    > > /sys/class/event_sources/core_pmu
    > > /sys/class/event_sources/uncore_pmu
    > >
    > > Then,
    > > /sys/devices/system/node/nodeN/node_events/event_source_id is a link
    > > to /sys/class/event_sources/uncore_pmu.
    >
    > > /sys/devices/system/cpu/cpuN/cpu_hardware_events/event_source_id is a
    > > link to /sys/class/event_sources/core_pmu.
    >
    > The other way around, look in /sys/class/*/, they're all symlinks.

    /sys/devices/system/cpu/cpu0/cpu_hw_events/*
    /sys/devices/system/cpu/cpu0/cpu_hw_cache_events/*
    /sys/devices/system/cpu/cpu0/cpu_raw_events/*
    ....
    ....
    /sys/devices/system/cpu/cpuN/cpu_hw_events/*
    /sys/devices/system/cpu/cpuN/cpu_hw_cache_events/*
    /sys/devices/system/cpu/cpuN/cpu_raw_events/*

    Is /sys/class/event_sources/* looks like,

    /sys/class/event_sources/cpu_hw_events0
    -> /sys/devices/system/cpu/cpu0/cpu_hw_events
    ...
    /sys/class/event_sources/cpu_hw_eventsN
    -> /sys/devices/system/cpu/cpuN/cpu_hw_events

    /sys/class/event_sources/cpu_hw_cache_events0
    -> /sys/devices/system/cpu/cpu0/cpu_hw_events
    ...
    /sys/class/event_sources/cpu_hw_cache_eventsN
    -> /sys/devices/system/cpu/cpuN/cpu_hw_events

    ?

    >
    > > And, the event_source_id
    > > #cat /sys/class/event_sources/core_pmu
    > > 0
    >
    > > #cat /sys/class/event_sources/uncore_pmu
    > > 1
    >
    > You can't cat a directory. You'd cat something
    > like: /sys/class/event_sources/core_pmu/event_source_id
    >
    > And they would contain PERF_TYPE_* like things.
    >
    > So for the current CPU PMUs we'd already create 3 event classes,
    > cpu_hw_events, cpu_hw_cache_events, cpu_raw_events, with resp.
    > event_source_id of 0, 3 and 4.
    >
    > The new PMUs will use a dynamic range that starts at PERF_TYPE_MAX.



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