Motivating Revolutionary Distributed Object Systems

1. Motivating Revolutionary Distributed Object Systems Andrew A. Chien achien@cs.uiuc.edu High Performance Distributed Objects Concurrent Systems Architecture Group Course WWW http://www-csag.cs.uiuc.edu/achien/cs491-f97/

2. Killer Networks are Here • Gigabit/second links are cheap, network interfaces are available • Std Network Configurations: 1996: 100mbit, 1998(?) Gigabit ethernet? • Hardware latencies in the 10’s of microseconds • Traditional problem: can’t get the performance to the application • Advances in supercomputing research have solved this problem • Direct user-level access and good low-level messaging kernels make this performance usable! “Fat Pipes” “Network Interface” “Network Interface”

3. 80 70 77 MB/s 60 50 Bandwidth (MB/s) 40 30 20 n1/2 10 0 1,024 4,096 16,384 65,536 4 16 64 256 Message size (bytes) Fast Messages Performance • Usable BW, 4us overhead, 11us latency • How fast an RPC can you do?

4. Fast Messages API • Multiprocess direct access • Memory mapped “contexts” • Dynamic process grouping, network namespace • Low-overhead layering of higher level API’s • Programmable Gather - Scatter • Multithreaded reassembly • Flow control to eliminate copies • Control over performance • Scheduling of computation and communication work • Accessible Performance • Typical message-size distributions can get bandwidth

5. API’s on FM: MPI • 70MB/s, 17ms latency, 5.1ms overhead • Very fast for a distributed system • Enables a new kind of distribution

6. MPI-FM Efficiency: FM API Evaluation • High Transfer Efficiency • For other systems: <25% for 1KB not unusual • Approaches 100%

7. Virtual Interface Architecture • Compaq/Intel/Microsoft Standard for Network Interfaces • Builds on work of • Fast Messages (Illinois) • Active Messages (Berkeley) • Shrimp (Princeton), U-NET (Cornell) • Provides for user-level protected access to the network • Fast protocols atop enable delivery of high performance communication • Enables commoditization as cluster and backbone interconnects • Myrinet, Servernet, Fibrechannel • Gigabit Ethernet! (this will be cheap)

8. CS 491 Projects: RPC on Steroids • DCOM Space “MS RPC on Fast Messages” • Explore software, find the right place to “surgically alter” • Performance analysis, Port, Reanalyze Performance • Java DO Space “Java RMI on Fast Messages” • Explore software, find the right place to “surgically alter” • Performance analysis, Port, Reanalyze Performance • 3-4 students on each project, this is small enough for you to do a great job (though there’s a clear learning curve) • … then adaptive remote invocation, object mobility… to support a vision for a new kind of distributed high performance computing

9. A Vision for Future LAN/CAN Computing • A much simpler programming model and flexible implementations • Single namespace for objects • Rapid remote invocation • Automatic object level placement, migration, load balance • Support for real-time • Support for fault-tolerance • What changes in the architecture of distributed applications does this imply?

10. Next Time • Fast messages API: delivering gigabit performance • Network usage model (dynamic, shared) • Challenges for these ambitious research goals • Naming • Consistency • Fault tolerance • Predictable Performance • Instrumentation • Think about your project, talk to your peers about it.