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    Subject[PATCH v4 00/22] perf: Add infrastructure and support for Intel PT
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    Hi Peter and all,

    This patchset adds support for Intel Processor Trace (PT) extension [1] of
    Intel Architecture that allows the capture of information about software
    execution flow, to the perf kernel infrastructure.

    The single most notable thing is that while PT outputs trace data in a
    compressed binary format, it will still generate hundreds of megabytes
    of trace data per second per core. Decoding this binary stream takes
    2-3 orders of magnitude the cpu time that it takes to generate
    it. These considerations make it impossible to carry out decoding in
    kernel space. Therefore, the trace data is exported to userspace as a
    zero-copy mapping that userspace can collect and store for later
    decoding. To address this, this patchset extends perf ring buffer with
    an "AUX space", which is allocated for hardware blocks such as PT to
    export their trace data with minimal overhead. This space can be
    configured via buffer's user page and mmapped from the same file
    descriptor with a given offset. Data can then be collected from it
    by reading the aux_head (write) pointer from the user page and updating
    aux_tail (read) pointer similarly to data_{head,tail} of the
    traditional perf buffer. There is an api between perf core and pmu
    drivers that wish to make use of this AUX space to export their data.

    For tracing blocks that don't support hardware scatter-gather tables,
    we provide high-order physically contiguous allocations to minimize
    the overhead needed for software double buffering and PMI pressure.

    This way we get a normal perf data stream that provides sideband
    information that is required to decode the trace data, such as MMAPs,
    COMMs etc, plus the actual trace in its own logical space.

    If the trace buffer is mapped writable, the driver will stop tracing
    when it fills up (aux_head approaches aux_tail), till data is read,
    aux_tail pointer is moved forward and an ioctl() is issued to
    re-enable tracing. If the trace buffer is mapped read only, the
    tracing will continue, overwriting older data, so that the buffer
    always contains the most recent data. Tracing can be stopped with an
    ioctl() and restarted once the data is collected.

    Another use case is annotating samples of other perf events: setting
    PERF_SAMPLE_AUX requests attr.aux_sample_size bytes of trace to be
    included in each event's sample.

    This patchset consists of necessary changes to the perf kernel
    infrastructure, and PT and BTS pmu drivers. The tooling support is not
    included in this series, however, it can be found in my github tree [2].

    This version changes the way watermarks are handled for AUX area and
    gets rid of the notion of "itrace" both in the core and in the perf
    interface (event attribute), which makes it more logical.

    [1] http://software.intel.com/en-us/intel-isa-extensions
    [2] http://github.com/virtuoso/linux-perf/tree/intel_pt

    Alexander Shishkin (21):
    perf: Add data_{offset,size} to user_page
    perf: Support high-order allocations for AUX space
    perf: Add a capability for AUX_NO_SG pmus to do software double
    buffering
    perf: Add a pmu capability for "exclusive" events
    perf: Redirect output from inherited events to parents
    perf: Add api for pmus to write to AUX space
    perf: Add AUX record
    perf: Support overwrite mode for AUX area
    perf: Add wakeup watermark control to AUX area
    perf: add ITRACE_START record to indicate that tracing has started
    x86: Add Intel Processor Trace (INTEL_PT) cpu feature detection
    x86: perf: Intel PT and LBR/BTS are mutually exclusive
    x86: perf: intel_pt: Intel PT PMU driver
    x86: perf: intel_bts: Add BTS PMU driver
    perf: Add rb_{alloc,free}_kernel api
    perf: Add a helper to copy AUX data in the kernel
    perf: Add a helper for looking up pmus by type
    perf: Add infrastructure for using AUX data in perf samples
    perf: Allocate ring buffers for inherited per-task kernel events
    perf: Allow AUX sampling for multiple events
    perf: Allow sampling of inherited events

    Peter Zijlstra (1):
    perf: Add AUX area to ring buffer for raw data streams

    arch/x86/include/asm/cpufeature.h | 1 +
    arch/x86/include/uapi/asm/msr-index.h | 18 +
    arch/x86/kernel/cpu/Makefile | 1 +
    arch/x86/kernel/cpu/intel_pt.h | 129 ++++
    arch/x86/kernel/cpu/perf_event.h | 14 +
    arch/x86/kernel/cpu/perf_event_intel.c | 14 +-
    arch/x86/kernel/cpu/perf_event_intel_bts.c | 501 +++++++++++++++
    arch/x86/kernel/cpu/perf_event_intel_ds.c | 11 +-
    arch/x86/kernel/cpu/perf_event_intel_lbr.c | 9 +-
    arch/x86/kernel/cpu/perf_event_intel_pt.c | 973 +++++++++++++++++++++++++++++
    arch/x86/kernel/cpu/scattered.c | 1 +
    include/linux/perf_event.h | 56 +-
    include/uapi/linux/perf_event.h | 69 +-
    kernel/events/core.c | 545 +++++++++++++++-
    kernel/events/internal.h | 50 ++
    kernel/events/ring_buffer.c | 310 ++++++++-
    16 files changed, 2658 insertions(+), 44 deletions(-)
    create mode 100644 arch/x86/kernel/cpu/intel_pt.h
    create mode 100644 arch/x86/kernel/cpu/perf_event_intel_bts.c
    create mode 100644 arch/x86/kernel/cpu/perf_event_intel_pt.c

    --
    2.1.0



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