linux-kernel - [PATCH 00/10] new mmap_read interfaces for ring buffer

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Date:   Tue, 10 Oct 2017 10:20:13 -0700
From:   kan.liang@...el.com
To:     acme@...nel.org, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     jolsa@...nel.org, wangnan0@...wei.com, hekuang@...wei.com,
        namhyung@...nel.org, alexander.shishkin@...ux.intel.com,
        adrian.hunter@...el.com, ak@...ux.intel.com,
        Kan Liang <kan.liang@...el.com>
Subject: [PATCH 00/10] new mmap_read interfaces for ring buffer

From: Kan Liang <kan.liang@...el.com>

The mmap_read interfaces for ring buffer has some issues
 - Not well organized. For example, perf record maintains some codes in
   builtin-record.c. Other perf tools use perf_mmap__read* functions to
   access ring buffer. Some of the codes should be shared.
 - Only support forward mode. Although there is
   perf_mmap__read_backward, no one use it. It's not well maintained.
   But perf top need to switch to overwrite backward mode for good
   performance.
 - There is bug found on overwrite backward mode.

The patch series will move all the mmap_read related code to evlist.c,
and provide new standard interfaces to access ring buffer.
The new interfaces include,
perf_evlist__mmap_read_init     //wrapper of perf_mmap__read_init
perf_mmap__read_init            //Initialization and calculate the range
perf_mmap__read_to_file		//read the ring buffer and write to file 
perf_mmap__read_event		//read the event in specified range
perf_mmap__read_done		//Update the md->prev for later use

For perf record, it needs to read all available data in ring buffer and
write them to perf.data file.
It can be done as below,
  perf_mmap__read_init
  perf_mmap__read_to_file
  perf_mmap__consume

For other perf tools, it needs to read and process events one by one.
It can be done as below,
  perf_mmap__read_init
  while (event = perf_mmap__read_event) {
    //process the event
    perf_mmap__consume
  }
  perf_mmap__read_done


All the stale interfaces will be removed, which include
perf_evlist__mmap_read
perf_evlist__mmap_read_forward
perf_evlist__mmap_read_backward
perf_evlist__mmap_read_catchup
perf_mmap__read_catchup
perf_mmap__read_forward
perf_mmap__read_backward

The patch series only changes the interfaces. It doesn't change the
core perf_mmap__read function. There is no functional change.

Kan Liang (10):
  perf record: new interfaces to read ring buffer to file
  perf tool: fix: Don't discard prev in backward mode
  perf tool: new functions to read event from ring buffer
  perf tool: perf_mmap__read_init wraper for evlist
  perf top: apply new mmap_read interfaces
  perf trace: apply new mmap_read interfaces
  perf kvm: apply new mmap_read interfaces
  perf python: apply new mmap_read interfaces
  perf tests: apply new mmap_read interfaces
  perf tool: remove stale mmap_read interfaces

 tools/perf/arch/x86/tests/perf-time-to-tsc.c |   9 +-
 tools/perf/builtin-kvm.c                     |  10 +-
 tools/perf/builtin-record.c                  | 111 +++---------
 tools/perf/builtin-top.c                     |   9 +-
 tools/perf/builtin-trace.c                   |   9 +-
 tools/perf/tests/backward-ring-buffer.c      |  10 +-
 tools/perf/tests/bpf.c                       |  10 +-
 tools/perf/tests/code-reading.c              |   8 +-
 tools/perf/tests/keep-tracking.c             |   8 +-
 tools/perf/tests/mmap-basic.c                |   9 +-
 tools/perf/tests/openat-syscall-tp-fields.c  |   9 +-
 tools/perf/tests/perf-record.c               |   9 +-
 tools/perf/tests/sw-clock.c                  |   8 +-
 tools/perf/tests/switch-tracking.c           |   8 +-
 tools/perf/tests/task-exit.c                 |   8 +-
 tools/perf/util/evlist.c                     | 244 +++++++++++++++++----------
 tools/perf/util/evlist.h                     |  31 ++--
 tools/perf/util/python.c                     |   9 +-
 18 files changed, 314 insertions(+), 205 deletions(-)

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2.5.5