On 12/22/09 2:32 PM, Gregory Haskins wrote: > On 12/22/09 2:25 PM, Avi Kivity wrote: >> >> If you're not doing something pretty minor, you're better of waking up a >> thread (perhaps _sync if you want to keep on the same cpu). With the >> new user return notifier thingie, that's pretty cheap. > > We have exploits that take advantage of IO heuristics. When triggered > they do more work in vcpu context than normal, which reduces latency > under certain circumstances. But you definitely do _not_ want to do > them in-atomic ;) And I almost forgot: dev->call() is an RPC to the backend device. Therefore, it must be synchronous, yet we dont want it locked either. I think that was actually the primary motivation for the change, now that I think about it. -Greg
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