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Operating System challenges in the petascale era and beyond Marc Shapiro Directeur de recherche Équipe Regal INRIA Paris-Rocquencourt & LIP6.

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Presentation on theme: "Operating System challenges in the petascale era and beyond Marc Shapiro Directeur de recherche Équipe Regal INRIA Paris-Rocquencourt & LIP6."— Presentation transcript:

1 Operating System challenges in the petascale era and beyond Marc Shapiro Directeur de recherche Équipe Regal INRIA Paris-Rocquencourt & LIP6

2 OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

3 OS Challenges beyond petascale Sometime in near future… Tomorrow: 10 3 CPUs on desktop × 10 6 across entreprise Heterogeneous: mobile phone to data centre Fat pipes ➚, core connectivity ➚ QoS variability ➚, latency ➙ Asynchronous, failure-prone ⇒ FLP

4 OS Challenges beyond petascale Classic architectures hitting a wall 10,000 1, ‘70‘80‘90‘00‘10 Power Density (W/cm 2 ) Pentium ® processors Hot Plate Nuclear Reactor Rocket Nozzle Sun’s Surface Intel Developer Forum, Spring Pat Gelsinger Heat dissipation ⇒ slow down clock ⇒ parallelism CPU Clock Speed DRAM Access Speed (MHz) Speed (MHz) 10,0001, Memory Wall ~90 cycles of the CPU clock to access main memory ! Modern Microprocessors - Jason Patterson Memory bottleneck ⇒ Replicate

5 OS Challenges beyond petascale Tsar multi-core interconnect CPU Crossbar micro-Ethernet L1 I Crossbar Cache memory CPU L1 I L1D CPU L1 I RAM L1D CPU L1 I L1D CPU L1 I L1D CPU L1 I L1D CPU L1 I CPU L1 I L1D Cache memory Source: Alain Greiner, LIP6

6 OS Challenges beyond petascale Users need cycles & storage New interaction models Cameras, microphones Surfaces, tablets, sensors Personal applications Personal search Constraint solvers What-if simulation Data mining Community applications Wikis, collaborative editing Social networks, games

7 OS Challenges beyond petascale Grid, Cloud Computing Data centres, clusters <10 6 nodes, stable, identified, trusted Move data to centre ✓ Economies of scale, problems outsourced ✓ Control - Expensive - End-to-end latency - Scalability, fault-tolerance ⇒ replicate to edge ⇒ consistency, edge issues Google = 300 TeraFLOPS

8 OS Challenges beyond petascale Edge, P2P Computing Large-scale, decentralised, self-organising > 10 6, churn, anonymous, untrusted Data, computation near source, use point ✓ Low marginal cost, management cost ✓ Low latency ✓ Fault independence, replication, scalability - Uncontrollable - Approximate results - Scalability, fault-tolerance ⇒ replicate ⇒ consistency issues = 3.3 PetaFLOPS Early adopters

9 OS Challenges beyond petascale First-person shooter

10 OS Challenges beyond petascale Game architectures FPS, MMOG-RPG, Virtual Worlds : Multi-server Game world partitioned in disjoint zones (kingdom, island) / server No interaction between players across servers Can change zones: complex communication Limitations Scalability with number of players Latency and bandwidth on Internet Working on server-less, P2P architecture Players exchange information directly

11 OS Challenges beyond petascale Petascale for the masses Massive parallelism + lots of resources No more just for the elite Decentralise to the edge Issues: Support for large-scale personal & community applications Mask complexity – Transparency, programmability – Autonomic control, graceful adaptation Control: virtual domains – Security, cost boundaries – Negotiate cost vs. guarantees

12 OS Challenges beyond petascale Distributed computing Modern computing is distributed sites / processes Asynchronous, costly messages Partial failures Redundant hardware Peer-to-peer : decentralised, self-organised, mass effect Amazon, Google, etc. : cheap PC, disks, etc., + redundancy

13 OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

14 OS Challenges beyond petascale Internet replication Pastry DHT Pastis P2P file system DHT: data storage & replication, fault independence Store file system blocks in DHT Self-organising, adaptive High availability, serverless file system Used in Internet set-top boxes

15 OS Challenges beyond petascale Scaling OS primitives to grids Hierarchical mutual exclusion Hierarchical failure detector Inter-cluster algorithm (2) Token ? (3) Token ? Cluster Algorithm

16 OS Challenges beyond petascale Grid4All (g4a): democratic grid Grid for schools, university educators, families, NGOs. Usability, decrease complexity Volatile, harsh environment Minimise manual administration costs Self-healing, -configuring, -tuning, etc. Dynamic VOs, available, scalable, decentralised Collaborative data-centric application scenarios

17 OS Challenges beyond petascale g4a Challenges Focus: Usability of Virtual Organisation mechanisms Lightweight, flexible, self-administering VOs Novel and collaborative applications Dynamic VOs Availability, scalability, decentralisation Techniques: Self-organising P2P infrastructure Autonomic management framework Federative and collaborative data services

18 OS Challenges beyond petascale g4a Virtual Organisations VO = Virtualised set of resources + names Virtualised group of users (members) Management: create, delete VOs, maintain membership, control resources, etc. VO-aware file system Private workspace per VO Expose files to workspace: remote link Fault tolerant, secure access to other users’ files P2P, localised, serverless, network transparent Read and write: best-effort consistency

19 OS Challenges beyond petascale School activity: Volcano simulation Digital simulation of volcano eruption What-if: fluidity, water table, etc. Explain Mt St Helens explosion CPU, data intensive Many experiments: provenance Collaborative work In class, between schools Also: edit report, etc. Adapt to available resources: Owned by schools Lent by families Bought from Cloud

20 OS Challenges beyond petascale Volcano Simulation workspace Paris 6 UPC NTUA VS'08 VO $$ Contribute Storage Simulation Files Files names federated into shared workspace external providers

21 OS Challenges beyond petascale Applications Core VO support VO management Distributed Components Overlay services Inter-VO services Resource information services Resource brokerage Collaborative & Federative services Semantic Store VO-oriented File System Execution service Fabric g4a architecture

22 OS Challenges beyond petascale g4a Autonomic Management Volatile resources, VOs, users, etc. Autonomic application, service Control loops respond automatically Await changes in environment Actuate appropriate changes Architecture is first-class High-level deployment and autonomic management primitives, language

23 OS Challenges beyond petascale MembershipDCMSDeploymtRsrc Mgt mgt g4a Deployment

24 OS Challenges beyond petascale mgt g4a Autonomic response MembershipDCMSDeploymtRsrc Mgt

25 OS Challenges beyond petascale g4a Decentralised Marketplace Economic approach to resource allocation Market Information System Aggregates resource information Technical, economic trade-offs Avoid supply / demand imbalance Decentralised, publish-subscribe model Currency Management Service: user accounts, market transactions

26 OS Challenges beyond petascale g4a Telex Semantic Store Shared documents updated by multiple users Online or offline Persistent in VOFS Detect and resolve conflicts: Directed by semantic information from application Decentralised; eventual convergence Separation of concerns

27 OS Challenges beyond petascale FLP = Fischer, Lynch, Patterson 85 Consensus = processes agree on value of 1 bit Impossible if: No upper bound on message delivery Failures not detectable Deterministic Sacrifice what? Safety? consensus algorithm makes mistakes Liveness? algorithm blocks Assumptions? FLP reigns!

28 OS Challenges beyond petascale Paxos Client 1 Client 2 Proposer 1 Proposer 2 Acceptor 1 Acceptor 2 Acceptor 3 Learner 1 Req(33) Prepare(1) Promise(1) Accepted(77) Response(77) Accept!(77) Choose leaderInstall value Accepted(33) Response(33) Accept!(33) Req(77) New instance, same leader

29 OS Challenges beyond petascale Byzantine fault-tolerant consensus Processes may collude, lie, etc.: models bugs, security attacks “He said…” To tolerate f faults ⇒ 3f+1 replicas Application: N-version programming database Maliciou s General Lieut. ALieut. B retreat!attack! He said “retreat!” General Lieut. A Lieut. B maliciou s attack! Lieut. C He said “retreat!” He said “attack!” attack! General Lieut. ALieut. B attack! He said “attack!” General Lieut. A Lieut. B maliciou s attack! He said “retreat!”

30 OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

31 OS Challenges beyond petascale Operating System challenges General-purpose: large-scale personal & community applications Mask complexity Parallel computing Fault-tolerant distributed computing Secure resource sharing Secure, consistent, replicated mutable shared data Energy conservation

32 OS Challenges beyond petascale Transparency To hide complexity: Design primitives that operate at several scales Message send = file write Local or remote RPC, distributed shared memory, single- level store, transaction, etc. “Leaky” abstractions: differing cost, failures, quality of service, guarantees ⇒ Transparency within limited, explicit domain “Create a domain for atomic multicast with a latency < 1 μs; join process A, B”

33 OS Challenges beyond petascale Domains Transparency within domain Cost, QoS, trust, etc., boundary Physical or virtual 1st class 5 CPU Crossbar micro-Ethernet L1IL1I Crossbar Cach e mem ory CPU L1IL1I L1DL1D L1IL1I RAM L1DL1D CPU L1IL1I L1DL1D L1IL1I L1DL1D L1IL1I L1DL1D L1IL1I L1IL1I L1DL1D L1DL1D L1DL1D Cach e mem ory

34 OS Challenges beyond petascale Massive multi-core programming Concurrent programming is for the masses Languages, proof tools Operating system abstractions – Event-driven computation – Software transactional memory – Support for speculative computing – Opportunistic computing (e.g. cache- first) Virtual machine – Execution environment – Garbage collection

35 OS Challenges beyond petascale Software transactional memory High-level concurrent programming primitive: Group of arbitrary memory access All-or-nothing, isolated, durable (in memory) ≈ composable Optimistic implementation, decent performance Raises level of abstraction (a bit) Non-transactional access? Big transactions? I/O? atomic { x := y * 2; y := z + x; if (t<0) retry; } atomic { t := x + 1; if (u<0) abort; }

36 OS Challenges beyond petascale Universal Virtual Machine Intermediate language for parallel, distributed programs Performance scalability: compile once, execute anywhere Hardware isolation: number of cores, cache sizes, instruction sets, CPU/GPU Expose useful parallelism Encapsulate Transactional Memory Affinity allocation & scheduling LLVM Dynamic hardware adaptation Run-time code generation for parallel machines

37 OS Challenges beyond petascale Secure and reliable communication Multi-scale group management Process group Dynamic join / leave (P2P: churn) Partial connectivity (firewalls, partitions) Failure detection Consensus primitives Transactions: memory, file system, communication Atomic Broadcast, Group Multicast Tolerate free-riders, colluding, etc. At different scales / different costs / different guarantees Replication and consistency

38 OS Challenges beyond petascale Architecture

39 OS Challenges beyond petascale Self-organisation Self-* = self-adminstration, self-healing, self- adapting, etc. Self-organising. Self-sustaining? Scalability = local approximation of global properties number of processors load Pool resources, hide complexity

40 OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

41 OS Challenges beyond petascale Summary Petascale for the masses Massive computing, storage is available Portal to fluid network Very non-uniform Cloud and Edge computing converge Asynchronous, failure-prone ⇒ FLP Concurrency inherently complex Formal verification is essential Transparency vs. control Energy = scarce resource, to be managed at all scales


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