Paolo Bonzini <pbonz...@redhat.com> writes: >> The problem with CPUs coming up late is indeed present in this patch, >> I'll review your patch on the flight. :) >> >> synchronize_rcu() is actually relatively cheap with URCU, so I guess >> that's fine. An alternative to that could be a pthread_barrier_t, but >> it can be added later. >> >> Another way to fix the issue with a variable number of waiters could be >> to wrap safe work with rcu_read_lock and rcu_read_unlock, and put a >> synchronize_rcu() at the beginning of the CPU thread function. But it >> can be done later too. >> >> Your patch from a year ago, right now, seems to be the best to me. I'd >> like to make it use regular work items instead of the special >> cpu->tcg_work_func, but that's pretty much it. > > Ok, I think I have something. It only uses condition variables when > there is a safe work in flight, to enter and leave the function at the > right time. It also makes linux-user's start_exclusive/end_exclusive > use the same synchronization logic. I'll test it and post; most > preliminary patches are straight from this series.
Good stuff, I look forward to seeing the patches. I'll see if I can come up with some better stress tests for linux-user in the meantime. > > Paolo -- Alex Bennée
