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    Subject[PATCH V9 0/4] Add the page size in the perf record (kernel)
    Date
    From: Kan Liang <kan.liang@linux.intel.com>

    Changes since V8
    - Drop active_mm which can cause kernel panic

    Changes since V7
    - Use active_mm to replace mm and init_mm
    - Update the commit message of the patch 1

    Changes since V6
    - Return the MMU page size of a given virtual address, not the kernel
    software page size
    - Add PERF_SAMPLE_DATA_PAGE_SIZE support for Power
    - Allow large PEBS for PERF_SAMPLE_CODE_PAGE_SIZE
    - Only include the kernel patches. The perf tool patches will be posted
    later separately once the kernel patches are accepted.

    Changes since V5
    - Introduce a new universal page walker for the page size in the perf
    subsystem.
    - Rebased on Peter's tree.

    Current perf can report both virtual addresses and physical addresses,
    but not the page size. Without the page size information of the utilized
    page, users cannot decide whether to promote/demote large pages to
    optimize memory usage.

    The patch set was submitted a year ago.
    https://lkml.kernel.org/r/1549648509-12704-1-git-send-email-kan.liang@linux.intel.com
    It introduced a __weak function, perf_get_page_size(), aim to retrieve
    the page size via a given virtual address in the generic code, and
    implemented a x86 specific version of perf_get_page_size().
    However, the proposal was rejected, because it's a pure x86
    implementation.
    https://lkml.kernel.org/r/20190208200731.GN32511@hirez.programming.kicks-ass.net

    At that time, it's not easy to support perf_get_page_size() universally,
    because some key functions, e.g., p?d_large, are not supported by some
    architectures.

    Now, the generic p?d_leaf() functions are added in the latest kernel.
    https://lkml.kernel.org/r/20191218162402.45610-2-steven.price@arm.com
    Starts from V6, a new universal perf_get_page_size() function is
    implemented based on the generic p?d_leaf() functions.

    On some platforms, e.g., X86, the page walker is invoked in an NMI
    handler. So the page walker must be NMI-safe and low overhead. Besides,
    the page walker should work for both user and kernel virtual address.
    The existing generic page walker, e.g., walk_page_range_novma(), is a
    little bit complex and doesn't guarantee the NMI-safe. The follow_page()
    is only for the user-virtual address. So a simpler page walk function is
    implemented here.

    Kan Liang (3):
    perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE
    perf/x86/intel: Support PERF_SAMPLE_DATA_PAGE_SIZE
    powerpc/perf: Support PERF_SAMPLE_DATA_PAGE_SIZE

    Stephane Eranian (1):
    perf/core: Add support for PERF_SAMPLE_CODE_PAGE_SIZE

    arch/powerpc/perf/core-book3s.c | 6 +-
    arch/x86/events/intel/ds.c | 11 ++-
    arch/x86/events/perf_event.h | 2 +-
    include/linux/perf_event.h | 2 +
    include/uapi/linux/perf_event.h | 6 +-
    kernel/events/core.c | 114 +++++++++++++++++++++++++++++++-
    6 files changed, 133 insertions(+), 8 deletions(-)

    --
    2.17.1

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