cpu-manager: accelerate pause() #16
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phip1611
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vmm/src/cpu.rs
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| let old = self.vcpus_pause_signalled.swap(true, Ordering::SeqCst); | ||
| if old { | ||
| // Make pause() idempotent. This is helpful when the migration | ||
| // thread wants to stop the vCPUS but the vCPU throttle thread | ||
| // also just performed a .pause(). We don't use strong | ||
| // synchronization between these threads in all cases, as every | ||
| // ms counts for the migration thread to reach a low downtime. | ||
| return Ok(()); |
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The throttle thread can only exit after resuming vcpus. I thus suggest reverting this part.
This reduces the time to pause all vCPUs from >254ms to 4ms for 254 CPUs. The speedup comes from decoupling the loop into two: - first signal all vCPUS - then wait for all vCPUs to ACK
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olivereanderson
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Accelerate cpu_manager.pause() massively.
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