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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 2 2008-09-18OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

3 3 2008-09-18OS 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 4 2008-09-18OS Challenges beyond petascale Classic architectures hitting a wall 10,000 1,000 100 10 1 ‘70‘80‘90‘00‘10 Power Density (W/cm 2 ) 4004 8008 8080 8085 8086 286 386 486 Pentium ® processors Hot Plate Nuclear Reactor Rocket Nozzle Sun’s Surface Intel Developer Forum, Spring 2004 - Pat Gelsinger Heat dissipation ⇒ slow down clock ⇒ parallelism CPU Clock Speed DRAM Access Speed (MHz) Speed (MHz) 10,0001,00010010 19901992199419961998200020022004 Memory Wall ~90 cycles of the CPU clock to access main memory ! Modern Microprocessors - Jason Patterson Memory bottleneck ⇒ Replicate

5 5 2008-09-18OS 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 6 2008-09-18OS 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 7 2008-09-18OS 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 8 2008-09-18OS 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 Folding@homeFolding@home = 3.3 PetaFLOPS Early adopters

9 9 2008-09-18OS Challenges beyond petascale First-person shooter http://steampowered.com

10 10 2008-09-18OS 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 11 2008-09-18OS 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 12 2008-09-18OS 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 13 2008-09-18OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

14 14 2008-09-18OS 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 15 2008-09-18OS Challenges beyond petascale Scaling OS primitives to grids Hierarchical mutual exclusion Hierarchical failure detector Inter-cluster algorithm (2) Token ? (3) Token ? Cluster Algorithm

16 16 2008-09-18OS 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 17 2008-09-18OS 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 18 2008-09-18OS 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 19 2008-09-18OS 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 20 2008-09-18OS 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 21 2008-09-18OS 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 22 2008-09-18OS 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 23 2008-09-18OS Challenges beyond petascale MembershipDCMSDeploymtRsrc Mgt mgt g4a Deployment

24 24 2008-09-18OS Challenges beyond petascale mgt g4a Autonomic response MembershipDCMSDeploymtRsrc Mgt

25 25 2008-09-18OS 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 26 2008-09-18OS 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 27 2008-09-18OS 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 28 2008-09-18OS 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 29 2008-09-18OS 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 30 2008-09-18OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

31 31 2008-09-18OS 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 32 2008-09-18OS 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 33 2008-09-18OS 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 34 2008-09-18OS 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 35 2008-09-18OS 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 36 2008-09-18OS 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 37 2008-09-18OS 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 38 2008-09-18OS Challenges beyond petascale Architecture

39 39 2008-09-18OS 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 40 2008-09-18OS Challenges beyond petascale Outline General-purpose computing in the petascale era and beyond State of the art Operating system challenges Summary

41 41 2008-09-18OS 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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