Towards Proving Optimistic Multicore Schedulers

Lepers, Baptiste; Zwaenepoel, Willy; Lozi, Jean-Pierre; Palix, Nicolas; Gouicem, Redha; Sopena, Julien; Lawall, Julia; Muller, Gilles

doi:10.1145/3102980.3102984

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…In a preliminary work [32], we introduced abstractions for proving WC (Section 2.2); the proofs require the absence of concurrent scheduling events during load balancing. No implementation was described.…”

Section: Related Workmentioning

confidence: 99%

Provable multicore schedulers with Ipanema

Lepers

Gouicem²,

Carver³

et al. 2020

Proceedings of the Fifteenth European Conference on Computer Systems

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Recent research and bug reports have shown that work conservation, the property that a core is idle only if no other core is overloaded, is not guaranteed by Linux's CFS or FreeBSD's ULE multicore schedulers. Indeed, multicore schedulers are challenging to specify and verify: they must operate under stringent performance requirements, while handling very large numbers of concurrent operations on threads. As a consequence, the verification of correctness properties of schedulers has not yet been considered. In this paper, we propose an approach, based on a domainspecific language and theorem provers, for developing schedulers with provable properties. We introduce the notion of concurrent work conservation (CWC), a relaxed definition of work conservation that can be achieved in a concurrent system where threads can be created, unblocked and blocked concurrently with other scheduling events. We implement several scheduling policies, inspired by CFS and ULE. We show that our schedulers obtain the same level of performance as production schedulers, while concurrent work conservation is satisfied.

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Section: Related Workmentioning

confidence: 99%

Provable multicore schedulers with Ipanema

Lepers

Gouicem²,

Carver³

et al. 2020

Proceedings of the Fifteenth European Conference on Computer Systems

Self Cite

View full text Add to dashboard Cite

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“…The DSL ensures, among other things, that the transitions for a process state are valid with regards to the specified automaton while a core never executes a blocked thread. After a recent study of defects inside the Completely Fair Scheduler of the GNU/Linux Kernel [18], Lepers et al [17] start to enhance Bossa with the objective of generating a proved optimistic multicore scheduler. SafePlace targets correct (VM) schedulers and also uses a formal language to ease the verification process.…”

Section: Related Workmentioning

confidence: 99%

Trustable virtual machine scheduling in a cloud

Hermenier

Henrio

2017

Proceedings of the 2017 Symposium on Cloud Computing

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In an Infrastructure As A Service (IaaS) cloud, the scheduler deploys VMs to servers according to service level objectives (SLOs). Clients and service providers must both trust the infrastructure. In particular they must be sure that the VM scheduler takes decisions that are consistent with its advertised behaviour. The difficulties to master every theoretical and practical aspects of a VM scheduler implementation leads however to faulty behaviours that break SLOs and reduce the provider revenues.We present SafePlace, a specification and testing framework that exhibits inconsistencies in VM schedulers. SafePlace mixes a DSL to formalise scheduling decisions with fuzz testing to generate a large spectrum of test cases and automatically report implementation faults.We evaluate SafePlace on the VM scheduler BtrPlace. Without any code modification, SafePlace allows to write test campaigns that are 3.83 times smaller than BtrPlace unit tests. SafePlace performs 200 tests per second, exhibited new non-trivial bugs, and outperforms the BtrPlace runtime assertion system. CCS CONCEPTS• Software and its engineering → Cloud computing; Software testing and debugging; Scheduling; KEYWORDS VM scheduling, software testing, specification language ACM Reference Format:

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Towards Proving Optimistic Multicore Schedulers

Cited by 2 publications

References 26 publications

Provable multicore schedulers with Ipanema

Provable multicore schedulers with Ipanema

Trustable virtual machine scheduling in a cloud

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