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    SubjectRe: [RFC][PATCH 09/11] perf_counter: revamp syscall input ABI
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    On Thu, 2009-03-19 at 09:15 +1100, Paul Mackerras wrote:
    > Peter Zijlstra writes:
    >
    > > Ah, I thought we should keep a pure 64 bit raw value. You never know
    > > what hardware will do.
    >
    > Oh I see, you use hw_event->raw_event if hw_event->raw is set. I
    > missed that before.
    >
    > Still, you're putting that into hwc->config along with other bits like
    > ARCH_PERFMON_EVENTSEL_USR and ARCH_PERFMON_EVENTSEL_OS, so I would
    > think we could spare two bits for the type, leaving 62 bits for the
    > raw event code. And if that isn't enough, there's the
    > hw_event.extra_config_len field, which allows userspace to pass in
    > arbitrary amounts of extra PMU configuration data.

    Good point, overflow interrupt, and usr/os/hv event filter and enable
    bits are usually in the config word.

    OK, how about the below? I didn't cut it to 2 bits, as that would
    already exhaust the TYPE space -- then again, 60 does feel cramped a
    bit..

    Index: linux-2.6/include/linux/perf_counter.h
    ===================================================================
    --- linux-2.6.orig/include/linux/perf_counter.h
    +++ linux-2.6/include/linux/perf_counter.h
    @@ -27,6 +27,12 @@ enum perf_event_types {
    PERF_TYPE_HARDWARE = 0,
    PERF_TYPE_SOFTWARE = 1,
    PERF_TYPE_TRACEPOINT = 2,
    +
    + /*
    + * available TYPE space, raw is the max value.
    + */
    +
    + PERF_TYPE_RAW = 15,
    };

    /*
    @@ -79,14 +85,8 @@ enum perf_counter_record_type {
    * Hardware event to monitor via a performance monitoring counter:
    */
    struct perf_counter_hw_event {
    - union {
    - __u64 raw_event;
    - struct {
    - __u64 event_id : 32,
    - type : 8,
    - __reserved_0 : 24;
    - };
    - };
    + __u64 event_id : 60,
    + type : 4;

    __u64 irq_period;
    __u64 record_type;
    @@ -94,7 +94,6 @@ struct perf_counter_hw_event {

    __u64 disabled : 1, /* off by default */
    nmi : 1, /* NMI sampling */
    - raw : 1, /* raw event type */
    inherit : 1, /* children inherit it */
    pinned : 1, /* must always be on PMU */
    exclusive : 1, /* only group on PMU */
    @@ -103,7 +102,7 @@ struct perf_counter_hw_event {
    exclude_hv : 1, /* ditto hypervisor */
    exclude_idle : 1, /* don't count when idle */

    - __reserved_1 : 54;
    + __reserved_1 : 55;

    __u32 extra_config_len;
    __u32 __reserved_4;



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