[Qemu-devel] [PATCH v5 00/10] aio_context_acquire/release pushdown, part 1

[Paolo Bonzini]

This is the first step of pushing down the AioContext lock.  Bottom halves
are already protected by their own lock, use it also for walking_bh
and for the handlers list (including walking_handlers).  The (lock,
walking_foo) pair is wrapped into the QemuLockCnt primitive.

The only difference from v3 is a smattering of tiny nice improvements
to QemuLockCnt.

Paolo

v4->v5:
        remove stray tabs [patchew]

v3->v4:
        Avoid useless atomic_mb_read in non-futex lockcnt [Stefan]
        Use atomic_read in qemu_lockcnt_count [Stefan]
        Tweak comment for qemu_lockcnt_cmpxchg_or_wait [Fam]
        Use if/else in qemu_lockcnt_dec_and_lock [Fam]
        Comment QEMU_LOCKCNT_STATE_* definitions [Fam]

v2->v3:
        fix missing unlock

v1->v2:
        rebased on top of polling patches
        moved documentation to include/
        new patch "aio-posix: split aio_dispatch_handlers out of aio_dispatch"
        replaced atomic_read with atomic_mb_read in qemu_lockcnt_inc
        replaced futex* function and macro names with qemu_futex*
        removed atomic access to node->pfd.revents (because there is no
          concurrent aio_poll anymore after the BDRV_POLL_WHILE series)
        left "aio: push aio_context_acquire/release down to dispatching"
          to a later series

Paolo Bonzini (10):
  aio: rename bh_lock to list_lock
  qemu-thread: introduce QemuLockCnt
  aio: make ctx->list_lock a QemuLockCnt, subsuming ctx->walking_bh
  qemu-thread: optimize QemuLockCnt with futexes on Linux
  aio-posix: split aio_dispatch_handlers out of aio_dispatch
  aio: tweak walking in dispatch phase
  aio-posix: remove walking_handlers, protecting AioHandler list with
    list_lock
  aio-win32: remove walking_handlers, protecting AioHandler list with
    list_lock
  aio: document locking
  async: optimize aio_bh_poll

 aio-posix.c                 | 116 +++++++------
 aio-win32.c                 |  83 +++++----
 async.c                     |  45 ++---
 docs/lockcnt.txt            | 277 +++++++++++++++++++++++++++++++
 docs/multiple-iothreads.txt |  13 +-
 include/block/aio.h         |  38 ++---
 include/qemu/futex.h        |  36 ++++
 include/qemu/thread.h       | 112 +++++++++++++
 util/Makefile.objs          |   1 +
 util/lockcnt.c              | 397 ++++++++++++++++++++++++++++++++++++++++++++
 util/qemu-thread-posix.c    |  35 +---
 util/qemu-thread-win32.c    |   2 +-
 util/trace-events           |  10 ++
 13 files changed, 1006 insertions(+), 159 deletions(-)
 create mode 100644 docs/lockcnt.txt
 create mode 100644 include/qemu/futex.h
 create mode 100644 util/lockcnt.c

-- 
2.9.3