[Qemu-devel] [PATCH v4 00/21] Extended I/O accounting

[Alberto Garcia <berto@igalia.com>]

Here's v4 of the series that implements extended I/O accounting for
block devices.

Since part of Max's BlockBackend series has already been merged, this
series can now be applied cleanly on top of the master branch without
additional dependencies.

Here's the summary of what this series provides:

 - New block_acct_failed() and block_acct_invalid() calls.
   We keep track now of the number of successful, failed and invalid
   operations (each one separated into read, write and flush). So from
   the API point of view, BlockDeviceStats contains 6 new fields for
   those.

 - idle_time_ns: time since the last I/O operation.

 - New BlockDeviceTimedStats struct: it has statistics for the I/O
   during a given interval of time. It keeps minimum, maximum and
   average latencies for read, write and flush operations.

   It also keeps the average read and write queue depths.

 - New 'stats-intervals' option that allows the user to define the
   intervals used to keep the aforementioned statistics. An arbitrary
   number of intervals can be specified, the length of each one is in
   seconds.

   For the API I opted for a colon-separated list of numbers,

      stats-intervals=60:3600:86400

   I also considered something a different syntax,

      stats-intervals.0.length=60,
      stats-intervals.1.length=3600,
      stats-intervals.2.length=86400

   This one could be useful if we want to specify any other attribute
   for each interval, but I couldn't come up with any, so I chose the
   simpler solution.

 - Two new options, stats-account-invalid and stats-account-failed,
   which allow the user to decide whether to count invalid and failed
   operations when computing the idle time and total latency.

Regards,

Berto

v4:
- Rebase on top of the current master. This series no longer depends
  on any other.
- patch 8: clarify that interval_length is in seconds [Stefan]
- patch 9: rewrite timed_average_sum() so it does not call
  qemu_clock_get_ns() twice [Stefan]

v3: https://lists.gnu.org/archive/html/qemu-block/2015-10/msg00785.html
- Rebased on top of the current master and on Max's BlockBackend
  series v7
- patch 4: minor documentation fixes [Stefan]
- patch 5: s/miliseconds/nanoseconds/ [Stefan]
- patch 6: dropped, there's no "supports_stats" anymore [Stefan]
- patch 7 (now 6): explain why block_acct_invalid() does not update
          total_time_ns[] [Stefan]
- patch 12 (now 11): don't initialize BlockAcctCookie to { 0 }, it's
           not needed.

v2: https://lists.gnu.org/archive/html/qemu-block/2015-10/msg00161.html
- First complete implementation of the new statistics

v1: https://lists.gnu.org/archive/html/qemu-devel/2015-06/msg03321.html
- Initial series containing only the timed average infrastructure.

Alberto Garcia (21):
  xen_disk: Account for flush operations
  ide: Account for write operations correctly
  block: define 'clock_type' for the accounting code
  util: Infrastructure for computing recent averages
  block: Add idle_time_ns to BlockDeviceStats
  block: Add statistics for failed and invalid I/O operations
  block: Allow configuring whether to account failed and invalid ops
  block: Compute minimum, maximum and average I/O latencies
  block: Add average I/O queue depth to BlockDeviceTimedStats
  block: New option to define the intervals for collecting I/O
    statistics
  qemu-io: Account for failed, invalid and flush operations
  block: Use QEMU_CLOCK_VIRTUAL for the accounting code in qtest mode
  iotests: Add test for the block device statistics
  nvme: Account for failed and invalid operations
  virtio-blk: Account for failed and invalid operations
  xen_disk: Account for failed and invalid operations
  atapi: Account for failed and invalid operations
  ide: Account for failed and invalid operations
  macio: Account for failed operations
  scsi-disk: Account for failed operations
  block: Update copyright of the accounting code

 block/accounting.c           | 123 ++++++++++++++-
 block/block-backend.c        |   1 +
 block/qapi.c                 |  51 +++++++
 blockdev.c                   |  53 +++++++
 hmp.c                        |   4 +-
 hw/block/nvme.c              |  11 +-
 hw/block/virtio-blk.c        |   4 +-
 hw/block/xen_disk.c          |  27 +++-
 hw/ide/atapi.c               |  31 ++--
 hw/ide/core.c                |  12 +-
 hw/ide/macio.c               |  12 +-
 hw/scsi/scsi-disk.c          |  46 ++++--
 include/block/accounting.h   |  28 ++++
 include/qemu/timed-average.h |  64 ++++++++
 qapi/block-core.json         | 103 ++++++++++++-
 qemu-io-cmds.c               |   9 ++
 qmp-commands.hx              |  80 +++++++++-
 tests/Makefile               |   4 +
 tests/qemu-iotests/136       | 349 +++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/136.out   |   5 +
 tests/qemu-iotests/group     |   1 +
 tests/test-timed-average.c   |  90 +++++++++++
 util/Makefile.objs           |   1 +
 util/timed-average.c         | 231 ++++++++++++++++++++++++++++
 24 files changed, 1292 insertions(+), 48 deletions(-)
 create mode 100644 include/qemu/timed-average.h
 create mode 100644 tests/qemu-iotests/136
 create mode 100644 tests/qemu-iotests/136.out
 create mode 100644 tests/test-timed-average.c
 create mode 100644 util/timed-average.c

-- 
2.6.1