[Qemu-devel] [PATCH v5 00/13] cpu-exec: Safe work in quiescent state

[Alex Bennée]

Hi,

I've picked up this work from Sergey and will be taking it forward
from now on.

Apart from adding my s-o-b tags to all the patches there are only two
changes. Both are to wait_safe_cpu_work function to prevent dead-lock
conditions.

First I have added the macro can_wait_for_safe() which compiles away
to 0 on SoftMMU. This will be tweaked in later MTTCG work.

Second I have ensured we signal the qemu_exclusive_cond conditional if
tcg_pending_threads is 0 by the time to we want to sleep waiting for
safe work to run.

Finally I've added another patch at the end of the series which
converts everything to a GArray. The main driver was my MTTCG test
case which was particularly stressing of memory as multi-thousand
queues of flushes backed up. I've since mitigated that with other
changes to the cputlb code but it does have the advantage of avoiding
bouncing the lock as we go through the queue. If people aren't happy
with the change we can always drop it.

I'm keen to get this work merged as soon as the tree re-opens so any
additional comments will be helpful.

I've been using this patch set along with the hot-path tweaks in
Paolo's tree as a base for the ongoing MTTCG patches. When I post the
next set of patches they will be based of this tree:

  https://github.com/stsquad/qemu/tree/mttcg/async-safe-work-v5

Which is:
  - v2.7.0-rc0
  - plus Reduce lock contention on TCG hot-path (v5, Paolo's tree)
  - plus cpu-exec: Safe work in quiescent state (v5, this series)

Alex Bennée (3):
  atomic: introduce atomic_dec_fetch.
  cpus: pass CPUState to run_on_cpu helpers
  cpu-exec: replace cpu->queued_work with GArray

Sergey Fedorov (10):
  cpus: Move common code out of {async_,}run_on_cpu()
  cpus: Wrap mutex used to protect CPU work
  cpus: Rename flush_queued_work()
  linux-user: Use QemuMutex and QemuCond
  linux-user: Rework exclusive operation mechanism
  linux-user: Add qemu_cpu_is_self() and qemu_cpu_kick()
  linux-user: Support CPU work queue
  bsd-user: Support CPU work queue
  cpu-exec-common: Introduce async_safe_run_on_cpu()
  tcg: Make tb_flush() thread safe

 bsd-user/main.c            |  16 +++++
 cpu-exec-common.c          | 157 +++++++++++++++++++++++++++++++++++++++++++++
 cpu-exec.c                 |  12 +---
 cpus.c                     | 108 ++++++-------------------------
 hw/i386/kvm/apic.c         |   3 +-
 hw/i386/kvmvapic.c         |   6 +-
 hw/ppc/ppce500_spin.c      |  31 +++------
 hw/ppc/spapr.c             |   6 +-
 hw/ppc/spapr_hcall.c       |  17 ++---
 include/exec/exec-all.h    |  31 +++++++++
 include/qemu/atomic.h      |   4 ++
 include/qom/cpu.h          |  30 ++++++---
 kvm-all.c                  |  21 ++----
 linux-user/main.c          |  94 +++++++++++++++++----------
 target-i386/helper.c       |  19 +++---
 target-i386/kvm.c          |   6 +-
 target-s390x/cpu.c         |   4 +-
 target-s390x/cpu.h         |   7 +-
 target-s390x/kvm.c         |  98 ++++++++++++++--------------
 target-s390x/misc_helper.c |   4 +-
 translate-all.c            |  17 +++--
 21 files changed, 420 insertions(+), 271 deletions(-)

-- 
2.7.4