On Tue, Apr 27, 2010 at 5:06 PM, Chunqiang (CQ) Tang <tang...@gmail.com> wrote:
> I just started to read the code of qemu-kvm-0.12.3 recently, and was
> puzzled by the thread synchronization issue in qcow2.c and
> qcow2-cluster.c. Could someone please enlighten me? Thanks!
Is this what you are looking for:
kvm-all.c:kvm_cpu_exec:
qemu_mutex_unlock_iothread();
ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);
qemu_mutex_lock_iothread();
and
vl.c:main_loop_wait:
ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
qemu_mutex_lock_iothread();
if (ret > 0) {
IOHandlerRecord *pioh;
QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
If I understand correctly the global iothread mutex prevents block
driver code from executing concurrently.
Stefan
