CS533 Concepts of Operating Systems Class 9 User-Level Remote Procedure Call

CS533 - Concepts of Operating Systems 2 Questions  Where does most of LRPC’s overhead come from?  How can the kernel be eliminated from the call path on SMMPs with user-level threads?  To a thread URPC is synchronous, but to the thread library it is asynchronous … explain.  Why do kernel thread switches have long term cache and TLB effects that user thread switches do not?

CS533 - Concepts of Operating Systems 3 Questions  In what ways does URPC do “cooperative scheduling” across address space boundaries?  In what ways does URPC do load balancing?  How does URPC affect throughput and latency?  Why might URPC scale better than kernel-based RPC?  How can a client’s CPU be hijacked by a server? o How could you solve this problem?

CS533 - Concepts of Operating Systems 4 Questions  Now we have scheduling, synchronization, and IPC outside the kernel o What should be IN the kernel? o Note, these papers predated scheduler activations  Second half of CS533 examines the evolution of kernel structuring approaches

CS533 - Concepts of Operating Systems 5 Reminder  Midterm exam on Thursday  Closed book  Questions on race conditions, deadlock, monitors, RCU, manual and automatic stack management, user- level threads, scheduler activations, RPC vs LRPC vs URPC

CS533 - Concepts of Operating Systems 6 What have we learned so far?  Multi-threaded programming primitives  Race conditions and deadlock problems  Monitors  Scalable synchronization on modern CPUs  Event-based programming instead of multi-threading  Manual vs automatic stack management  Cooperative scheduling (task management)  Kernel support for user-level threads  RPC and various optimizations (LRPC & URPC)