diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-06-18 18:47:19 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-07-01 15:45:50 +0200 |
| commit | afbe70535ff1a8a7a32910cc15ebecc0ba92e7da (patch) | |
| tree | 1e12a91857ba9ce038e7c1c05fd901add373b36b /stubs | |
| parent | 2e7f7a3c86f884a77296a137b7c730a4d580c5c9 (diff) | |
main-loop: introduce qemu_mutex_iothread_locked
This function will be used to avoid recursive locking of the iothread lock
whenever address_space_rw/ld*/st* are called with the BQL held, which is
almost always the case.
Tracking whether the iothread is owned is very cheap (just use a TLS
variable) but requires some care because now the lock must always be
taken with qemu_mutex_lock_iothread(). Previously this wasn't the case.
Outside TCG mode this is not a problem. In TCG mode, we need to be
careful and avoid the "prod out of compiled code" step if already
in a VCPU thread. This is easily done with a check on current_cpu,
i.e. qemu_in_vcpu_thread().
Hopefully, multithreaded TCG will get rid of the whole logic to kick
VCPUs whenever an I/O event occurs!
Cc: Frederic Konrad <fred.konrad@greensocs.com>
Message-Id: <1434646046-27150-3-git-send-email-pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'stubs')
| -rw-r--r-- | stubs/iothread-lock.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/stubs/iothread-lock.c b/stubs/iothread-lock.c index 5d8aca1b37..dda6f6b58d 100644 --- a/stubs/iothread-lock.c +++ b/stubs/iothread-lock.c @@ -1,6 +1,11 @@ #include "qemu-common.h" #include "qemu/main-loop.h" +bool qemu_mutex_iothread_locked(void) +{ + return true; +} + void qemu_mutex_lock_iothread(void) { } |