[Qemu-devel] [RFC 0/7] dataplane: switch to N:M devices-per-thread model

[Stefan Hajnoczi]

This series moves the event loop thread out of dataplane code.  It makes
-iothread id=foo a separate concept.  This makes it possible to bind several
devices to the same iothread.

Syntax:

  qemu -iothread id=iothread0 \
       -device virtio-blk-pci,iothread=iothread0,x-data-plane=on,...

For backwards-compatibility the iothread= parameter can be omitted.  A
per-device IOThread will be created behind the scenes (just like the old 1:1
threading model).

This series includes the aio_context_acquire/release API which makes it easy to
synchronize access to AioContext across threads.

The IOThread object is really a stand-in for Michael Roth's QContext.  They
both have the same purpose but I needed something to develop against while
QContext is unfinished.  In order to make progress I'd like to agree on the
user-visible API that IOThread/QContext presents.  That way QContext can be
implemented step-by-step without holding up dataplane.

Finally, the -iothread command-line option will soon be replaced with -object.
I am following Igor's work in the area and will try to help get that code in.

Stefan Hajnoczi (7):
  rfifolock: add recursive FIFO lock
  aio: add aio_context_acquire() and aio_context_release()
  iothread: add I/O thread object
  iothread: command-line option
  qdev: add get_pointer_and_free() for temporary strings
  iothread: add "iothread" qdev property type
  dataplane: replace internal thread with IOThread

 Makefile.objs                    |   1 +
 async.c                          |  18 +++++
 hw/block/dataplane/virtio-blk.c  |  91 ++++++++++++-----------
 hw/core/qdev-properties-system.c |  65 +++++++++++++++++
 include/block/aio.h              |  18 +++++
 include/hw/qdev-properties.h     |   3 +
 include/hw/virtio/virtio-blk.h   |   8 ++-
 include/qemu/rfifolock.h         |  54 ++++++++++++++
 include/sysemu/iothread.h        |  32 +++++++++
 include/sysemu/sysemu.h          |   1 +
 iothread.c                       | 152 +++++++++++++++++++++++++++++++++++++++
 qemu-options.hx                  |   8 +++
 tests/Makefile                   |   2 +
 tests/test-aio.c                 |  58 +++++++++++++++
 tests/test-rfifolock.c           |  90 +++++++++++++++++++++++
 util/Makefile.objs               |   1 +
 util/rfifolock.c                 |  78 ++++++++++++++++++++
 vl.c                             |  12 ++++
 18 files changed, 647 insertions(+), 45 deletions(-)
 create mode 100644 include/qemu/rfifolock.h
 create mode 100644 include/sysemu/iothread.h
 create mode 100644 iothread.c
 create mode 100644 tests/test-rfifolock.c
 create mode 100644 util/rfifolock.c

-- 
1.8.4.2