On 11/28/2013 11:53 AM, Paolo Bonzini wrote:
Il 28/11/2013 10:49, Avi Kivity ha scritto:
Linux is safe, it does interrupt migration from within the interrupt
handler. If you do that before the device-specific EOI, you won't get
another interrupt until programming the MSI is complete.
Is virtio safe? IIRC it can post multiple interrupts without guest acks.
Using call_rcu() is a better solution than srcu IMO. Less code changes,
consistently faster.
call_rcu() has the problem of rate limiting, too. It wasn't such a
great idea, I think.
The QRCU I linked would work great latency-wise (it has roughly the same
latency of an rwsem but readers are lock-free). However, the locked
operations in the read path would hurt because of cache misses, so it's
not good either.
I guess srcu would work. Do you know what's the typical write-side
latency there? (in terms of what it waits for, not nanoseconds).
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