Lightweight Remote Procedure Call

BRIAN N. BERSHAD, THOMAS E. ANDERSON, EDWARD D. LASOWSKA,

AND HENRY M. LEVYUNIVERSTY OF WASHINGTON

"Lightweight Remote Procedure Call" by B. N. Bershad, T. E. Anderson, E. D. Lazowska, and H. M. Levy, Proceedings of the 12th Symposium on Operating Systems Principles, pp. 102-113, December 1989.

PRESENTER: ALIREZA GOUDARZIJan 27, 2010

alirezag@cecs.pex.eduCS 533 , Winter 2020 , John Walpole

Waves of Computing Paradigms

Centralized

Virtualization & Cloud

Distributed

Limited capacity , expensive , hard to manage , low reliability ….

Ubiquitous computing

You are here

Distributed Computing

OS

Machine

RPC: Inter-machine communication with abstraction of a procedure call.

• Each machine run a monolithic kernel OS• Distributed application talk to each other• Machines ( OS ) talk to each other

• Domain of protection is an entire machine• OS internally is one piece

OS

Machine

OS

Machine

OS

Machine

Emergence of Microkernel in OS

Modularity correctness hit the kernel atmosphere

From Wikipedia : http://en.wikipedia.org/wiki/Architecture_of_Windows_NT

Microkernel Implications

• Separate components • Separate protection domains– Might or might now sharing the same address

space• Component inter-comm. in a shared memory

conventional IPC

What’s wrong with that ?

IPC

• way too much coupling between components– Logic and semantics of components are exposed

• Defies the purpose of modular design• Difficult to use• Control flow transfer is awkward

?You are here

What’s the problem?

THE BIG PROBLEM

• Control flow transfer• Data transfer• Separate address space • On a same memory space

RPC

• Syntax of a procedure call• Semantics of a procedure call• But!....

RPC : Control Flow / Data Transfer

Client Kernel Server

4 context switch , 4 buffer copy , expensive access validation , expensive stubsExpensive scheduling

Different naming but gist of it is that these are separate address spaces ( might be in the same shared memory or not ) and to give them access to the data you have to copy the data back and forth

Any Alternatives?

Protected Procedure Call

• Each object is protected with an Access Control List (ACL)

• Different objects can access each other if their have the right permission to another object.

• Then an object can call a procedure if it has sufficient right to do so.

• But….

Protected Procedure Call

• It is just a procedure call.• Within a single address space• address space / protection domain

=> NO REAL IPC

Solution

Lightweight Remote Procedure Call

IPC semantics of remote procedure call

Efficiency of protected procedure call

+

=

Lightweight-RPC : The Middle Way

• Observations in RPC systems : – Most communications are not cross-machines– Most attributes are simple not complex

• LRPC as a RPC exploiting the single machine boundary.

Main Gains

• Simple control transfer ( b/w addr. spaces)• Simple data transfer ( b/w addr. spaces)• Simple stubs ( low overhead ) • Designing with single-machine-concurrency in

mind.

LRPC Call: Control Flow TransferProcedure Call ( hand-off scheduling)• Semantics imply we can safely bypass

scheduler ! Why?• We can invoke the server procedure with only

one formal call !!! How?

LRPC: Call

Client

Stub

Kernel

Stub

Server

A-Stack

L-Stack E-Stack

P-ID

U-thread + Server Stack

2- Copy of Param.

1- call

3 – prepare the context

4-upcall

LRPC Call : Multiprocessor

• TLB miss problem in server domain• CPU context caching in multiprocessor system• CPU idles on server / client domain– CPU context migration is cheaper than flushing

and reloading TLB• No locks only one for each A-stack queue in

client stub.

LRPC: Binding

• How does validation work? ( call / return ) • How does client find the server?• How does kernel allocate and manage

memory?

LRPC Binding: Client Import

Client

Stub

Kernel

Stub

Server

1- registration

2- listening

A-Stack

3- request

Binding O

4- binding

L-Stack E-Stack

PDL3- response

Special Cases

• Between Machine Calls• Complex/Large Params.• Termination

Q & A

You are here