[Qemu-devel] [RFC PATCH V3 0/3] Multithread TCG async_safe_work part.

[fred . konrad]

From: KONRAD Frederic <address@hidden>

This is the async_safe_work introduction bit of the Multithread TCG work.
Rebased on current upstream (6169b60285fe1ff730d840a49527e721bfb30899).

(Currently untested as I need to rebase MTTCG first.)

It can be cloned here:
http://git.greensocs.com/fkonrad/mttcg.git branch async_work_v3

The first patch introduces a mutex to protect the existing queued_work_*
CPUState members against multiple (concurent) access.

The second patch introduces a tcg_exec_flag which will be 1 when we are inside
cpu_exec(), -1 when we must not enter the cpu execution and 0 when we are
allowed to do so. This is required as safe work need to be sure that's all vCPU
are outside cpu_exec().

The last patch introduces async_safe_work. It allows to add some work which will
be done asynchronously but only when all vCPUs are outside cpu_exec(). The tcg
thread will wait that no vCPUs have any pending safe work before reentering
cpu-exec().

Changes V2 -> V3:
  * Check atomically we are not in the executiong loop to fix the race condition
    which might happen.
Changes V1 -> V2:
  * Release the lock while running the callback for both async and safe work.

KONRAD Frederic (3):
  cpus: protect queued_work_* with work_mutex.
  cpus: add tcg_exec_flag.
  cpus: introduce async_run_safe_work_on_cpu.

 cpu-exec.c        |  10 ++++
 cpus.c            | 160 ++++++++++++++++++++++++++++++++++++++++--------------
 include/qom/cpu.h |  57 +++++++++++++++++++
 qom/cpu.c         |  20 +++++++
 4 files changed, 207 insertions(+), 40 deletions(-)

-- 
1.9.0