[PATCH experiment 00/35] stackless coroutine backend

[Paolo Bonzini <pbonzini@redhat.com>]

Here is an experiment with using stackless coroutines in QEMU.  It
only compiles enough code to run tests/unit/test-coroutine, but at
least it proves that it's possible to quickly test ideas in the
area of coroutine runtimes.  Another idea that could be toyed with
in a similar manner could be (whoa) C++ coroutines.

As expected, this also found some issues in existing code, so I
plan to submit patches 1-5 separately.

The new backend (which is the only one that works, due to the required
code changes) is in patch 7.  For the big description of what stackless
coroutines are, please refer to that patch.

Patches 8-11 do some initial conversions.  Patch 12 introduce some
preprocessor magic that greatly eases the rest of the work, and then
the tests are converted one at a time, until patch 27 where the only
ones missing are the CoRwlock tests.

Therefore, patches 28-33 convert CoRwlock and pathces 34-35 take care
of the corresponding tests, thus concluding the experiment.

Paolo

Paolo Bonzini (35):
  coroutine: add missing coroutine_fn annotations for CoRwlock functions
  coroutine: qemu_coroutine_get_aio_context is not a coroutine_fn
  coroutine: introduce QemuCoLockable
  coroutine: introduce coroutine_only_fn
  coroutine: small code cleanup in qemu_co_rwlock_wrlock
  disable some code
  coroutine: introduce the "stackless coroutine" backend
  /basic/lifecycle
  convert qemu-coroutine-sleep.c to stackless coroutines
  enable tail call optimization of qemu_co_mutex_lock
  convert CoMutex to stackless coroutines
  define magic macros for stackless coroutines
  /basic/yield
  /basic/nesting
  /basic/self
  /basic/entered
  /basic/in_coroutine
  /basic/order
  /perf/lifecycle
  /perf/nesting
  /perf/yield
  /perf/function-call
  /perf/cost
  /basic/no-dangling-access
  /locking/co-mutex
  convert qemu_co_mutex_lock_slowpath to magic macros
  /locking/co-mutex/lockable
  qemu_co_rwlock_maybe_wake_one
  qemu_co_rwlock_rdlock
  qemu_co_rwlock_unlock
  qemu_co_rwlock_downgrade
  qemu_co_rwlock_wrlock
  qemu_co_rwlock_upgrade
  /locking/co-rwlock/upgrade
  /locking/co-rwlock/downgrade

 configure                    |  44 +---
 include/qemu/co-lockable.h   | 110 +++++++++
 include/qemu/coroutine.h     |  99 ++++++--
 include/qemu/coroutine_int.h |   6 -
 include/qemu/lockable.h      |  13 +-
 include/qemu/typedefs.h      |   1 +
 tests/unit/meson.build       |   2 +-
 tests/unit/test-coroutine.c  | 425 +++++++++++++++++++++++++++++------
 util/coroutine-stackless.c   | 159 +++++++++++++
 util/meson.build             |  10 +-
 util/qemu-coroutine-lock.c   | 215 ++++++++++++++----
 util/qemu-coroutine-sleep.c  |  57 ++++-
 util/qemu-coroutine.c        |  18 +-
 13 files changed, 932 insertions(+), 227 deletions(-)
 create mode 100644 include/qemu/co-lockable.h
 create mode 100644 util/coroutine-stackless.c

-- 
2.35.1