[RFC PATCH v2 0/3] perf core/perf tools: Utilizing overwrite ring buffer

[Wang Nan <wangnan0@huawei.com>]

This patch set explores the idea shown in [1], which puts size of every
events at the end of them in ring buffer so user space tool like perf
can parse the ring buffer backward and find the oldest event in it.

In this version:

 - Kernel side, rename PERF_SAMPLE_SIZE to PERF_SAMPLE_SIZE_AT_END,
   output 8 bytes to meet the alignment requirement.

 - Perf side, provide a prototype utilize this feature. With this
   prototype users are allowed to capture the last events in an
   overwrite ring buffer using:

   # ./perf record -e dummy -e syscalls:*/overwrite/ ...

[1] http://lkml.kernel.org/g/1449063499-236703-1-git-send-email-wangnan0@huawei.com

Wang Nan (3):
  perf/core: Put size of a sample at the end of it
  perf tools: Enable overwrite settings
  perf record: Find tail pointer through size at end of event

 include/uapi/linux/perf_event.h |  3 +-
 kernel/events/core.c            |  9 +++++
 tools/perf/builtin-record.c     | 76 +++++++++++++++++++++++++++++++++++++++--
 tools/perf/perf.h               |  2 ++
 tools/perf/util/evlist.c        | 42 +++++++++++++++++------
 tools/perf/util/evsel.c         |  7 ++++
 tools/perf/util/evsel.h         |  3 ++
 tools/perf/util/parse-events.c  | 14 ++++++++
 tools/perf/util/parse-events.h  |  4 ++-
 tools/perf/util/parse-events.l  |  2 ++
 10 files changed, 147 insertions(+), 15 deletions(-)

-- 
1.8.3.4