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  1. 29 8月, 2014 3 次提交
    • P
      AioContext: introduce aio_prepare · a3462c65
      由 Paolo Bonzini 提交于 
      This will be used to implement socket polling on Windows.
On Windows, select() and g_poll() are completely different;
sockets are polled with select() before calling g_poll,
and the g_poll must be nonblocking if select() says a
socket is ready.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      a3462c65
    • P
      AioContext: export and use aio_dispatch · e4c7e2d1
      由 Paolo Bonzini 提交于 
      So far, aio_poll's scheme was dispatch/poll/dispatch, where
the first dispatch phase was used only in the GSource case in
order to avoid a blocking poll.  Earlier patches changed it to
dispatch/prepare/poll/dispatch, where prepare is aio_compute_timeout.

By making aio_dispatch public, we can remove the first dispatch
phase altogether, so that both aio_poll and the GSource use the same
prepare/poll/dispatch scheme.

This patch breaks the invariant that aio_poll(..., true) will not block
the first time it returns false.  This used to be fundamental for
qemu_aio_flush's implementation as "while (qemu_aio_wait()) {}" but
no code in QEMU relies on this invariant anymore.  The return value
of aio_poll() is now comparable with that of g_main_context_iteration.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      e4c7e2d1
    • P
      AioContext: take bottom halves into account when computing aio_poll timeout · 845ca10d
      由 Paolo Bonzini 提交于 
      Right now, QEMU invokes aio_bh_poll before the "poll" phase
of aio_poll.  It is simpler to do it afterwards and skip the
"poll" phase altogether when the OS-dependent parts of AioContext
are invoked from GSource.  This way, AioContext behaves more
similarly when used as a GSource vs. when used as stand-alone.

As a start, take bottom halves into account when computing the
poll timeout.  If a bottom half is ready, do a non-blocking
poll.  As a side effect, this makes idle bottom halves work
with aio_poll; an improvement, but not really an important
one since they are deprecated.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      845ca10d
  3. 09 7月, 2014 1 次提交
    • P
      AioContext: speed up aio_notify · 0ceb849b
      由 Paolo Bonzini 提交于 
      In many cases, the call to event_notifier_set in aio_notify is unnecessary.
In particular, if we are executing aio_dispatch, or if aio_poll is not
blocking, we know that we will soon get to the next loop iteration (if
necessary); the thread that hosts the AioContext's event loop does not
need any nudging.

The patch includes a Promela formal model that shows that this really
works and does not need any further complication such as generation
counts.  It needs a memory barrier though.

The generation counts are not needed because any change to
ctx->dispatching after the memory barrier is okay for aio_notify.
If it changes from zero to one, it is the right thing to skip
event_notifier_set.  If it changes from one to zero, the
event_notifier_set is unnecessary but harmless.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      0ceb849b
  5. 04 6月, 2014 1 次提交
  7. 13 3月, 2014 1 次提交
    • S
      aio: add aio_context_acquire() and aio_context_release() · 98563fc3
      由 Stefan Hajnoczi 提交于 
      It can be useful to run an AioContext from a thread which normally does
not "own" the AioContext.  For example, request draining can be
implemented by acquiring the AioContext and looping aio_poll() until all
requests have been completed.

The following pattern should work:

  /* Event loop thread */
  while (running) {
      aio_context_acquire(ctx);
      aio_poll(ctx, true);
      aio_context_release(ctx);
  }

  /* Another thread */
  aio_context_acquire(ctx);
  bdrv_read(bs, 0x1000, buf, 1);
  aio_context_release(ctx);

This patch implements aio_context_acquire() and aio_context_release().

Note that existing aio_poll() callers do not need to worry about
acquiring and releasing - it is only needed when multiple threads will
call aio_poll() on the same AioContext.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      98563fc3
  9. 23 8月, 2013 3 次提交
  11. 19 8月, 2013 1 次提交
  13. 19 7月, 2013 1 次提交
  15. 15 3月, 2013 1 次提交
    • S
      aio: add a ThreadPool instance to AioContext · 9b34277d
      由 Stefan Hajnoczi 提交于 
      This patch adds a ThreadPool to AioContext.  It's possible that some
AioContext instances will never use the ThreadPool, so defer creation
until aio_get_thread_pool().

The reason why AioContext should have the ThreadPool is because the
ThreadPool is bound to a AioContext instance where the work item's
callback function is invoked.  It doesn't make sense to keep the
ThreadPool pointer anywhere other than AioContext.  For example,
block/raw-posix.c can get its AioContext's ThreadPool and submit work.

Special note about headers: I used struct ThreadPool in aio.h because
there is a circular dependency if aio.h includes thread-pool.h.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
      9b34277d
  17. 22 2月, 2013 1 次提交
  19. 19 12月, 2012 2 次提交
  21. 11 12月, 2012 1 次提交
  23. 13 11月, 2012 1 次提交
  25. 30 10月, 2012 6 次提交
  27. 01 5月, 2012 1 次提交
  29. 27 4月, 2012 1 次提交
  31. 22 10月, 2011 1 次提交
  33. 06 9月, 2011 1 次提交
    • K
      async: Allow nested qemu_bh_poll calls · 648fb0ea
      由 Kevin Wolf 提交于 
      qemu may segfault when a BH handler first deletes a BH and then (possibly
indirectly) calls a nested qemu_bh_poll(). This is because the inner instance
frees the BH and deletes it from the list that the outer one processes.

This patch deletes BHs only in the outermost qemu_bh_poll instance.

Commit 7887f620 already tried to achieve the same, but it assumed that the BH
handler would only delete its own BH. With a nested qemu_bh_poll(), this isn't
guaranteed, so that commit wasn't enough. Hope this one fixes it for real.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      648fb0ea
  35. 21 8月, 2011 1 次提交
  37. 02 8月, 2011 1 次提交
    • K
      async: Remove AsyncContext · 384acbf4
      由 Kevin Wolf 提交于 
      The purpose of AsyncContexts was to protect qcow and qcow2 against reentrancy
during an emulated bdrv_read/write (which includes a qemu_aio_wait() call and
can run AIO callbacks of different requests if it weren't for AsyncContexts).

Now both qcow and qcow2 are protected by CoMutexes and AsyncContexts can be
removed.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      384acbf4
  39. 15 6月, 2011 1 次提交
  41. 28 10月, 2009 2 次提交