Re: [Qemu-devel] [RFC 00/38] MTTCG: i386, user+system mode

[Emilio G. Cota]

On Sun, Aug 23, 2015 at 19:01:28 -0700, Paolo Bonzini wrote:
> >   * tb_flush: do it once all other CPUs have been put to sleep by calling
> >     rcu_synchronize().
> >     We also instrument tb_lock to make sure that only one tb_flush request 
> > can
> >     happen at a given time.
> 
> What do you think about just protecting code_gen_buffer with RCU?

I'm not sure of what you mean. Isn't essentially that what the
mechanism I sent (cpu_tcg_sched_work) is doing? I mean, the assumption
is: if any thread is on an RCU read critical section, then code_gen_buffer
cannot be modified. That's why tb_flush is only called after
rcu_synchronize() returns, to make sure that no existing threads
are executing code from the buffer.

                Emilio