Re: [Qemu-devel] Block I/O outside the QEMU global mutex was "Re: [RFC PATCH 00/17] Support for multiple "AIO contexts""

[Avi Kivity]

On 10/09/2012 02:18 PM, Jan Kiszka wrote:
> Not sure about the full context of this discussion, but I played with
> "stop-machine" (pause_all_vcpus) recently. The problem is, at least ATM,
> that it drops the BQL to wait for those threads, and that creates an
> unexpected rescheduling point over which a lot of code stumbles. But if
> this case here is about new, accordingly written code that is also not
> called from unprepared corners, it may work.

In theory we could make qemu_mutex_lock() detect that it's being
stop_machine()d and loop there - stop_machine() would just keep the lock
held.  But that's not doable easily with pthreads (there is no
mutex_lock_interruptible() equivalent).

In any case I've cooled down on stop_machine(), see sibling reply.

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error compiling committee.c: too many arguments to function