The RCU-Reader Preemption Problem in VMs

Prasad, Aravinda and Gopinath, K and McKenney, Paul E (2017) The RCU-Reader Preemption Problem in VMs. In: USENIX Annual Technical Conference (USENIX ATC), JUL 12-14, 2017, Santa Clara, CA, pp. 265-270.

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Abstract

When synchronization primitives such as locking and read-copy update (RCU) execute within virtual machines (VMs), preemption can cause multi-second latency spikes, increasing peak memory footprint and fragmentation inside VMs, which in turn may trigger swapping or VM ballooning. The resulting CPU utilization and memory footprint increases can negate the server consolidation benefits of virtualization. Although preemption of lock holders in VMs has been well-studied, the corresponding solutions do not apply to RCU due to its exceedingly lightweight read-side primitives. This paper presents the first evaluation of RCU-reader preemption in a virtualized environment. Our evaluation shows 50% increase in the peak memory footprint and 155% increase in fragmentation for a microbenchmark, 23.71% increase in average kernel CPU utilization, 2.9 x increase in the CPU time to compute a grace period and 2.18 x increase in the average grace period duration for the Postmark benchmark.

Item Type:	Conference Proceedings
Publisher:	USENIX ASSOC, SUITE 215, 2560 NINTH ST, BERKELEY, CA 94710 USA
Additional Information:	Copy right for this article belong to USENIX ASSOC, SUITE 215, 2560 NINTH ST, BERKELEY, CA 94710 USA
Department/Centre:	Division of Interdisciplinary Sciences > Supercomputer Education & Research Centre
Date Deposited:	17 Apr 2018 15:28
Last Modified:	17 Apr 2018 15:28
URI:	http://eprints.iisc.ac.in/id/eprint/59615

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