Intel Single Chip Cloud Computer (SCC) – An Overview

by

Karthik.V.M.

Motivations for SCC[1]

Many-core processor research High-performance power-efficient fabric Fine-grain power management Message-based programming support

Parallel Programming Research Better support for scale-out model servers

OS, Communication architecture Scale out programming model for client

Programming languages, runtimes

Courtesy: intel

SCC Feature Set

First Si with 48 iA cores on a single die Power envelope 125W, Core @ 1GHz, Mesh @

2GHz Message passing architecture

No coherent shared memory Proof of concept for scalable many-core solution

Next generation 2D mesh interconnect Bisection B/W 1.5Tb/s to 2Tb/s, avg.power 6W to

12 W Fine grain dynamic power management

Courtesy: intel

SCC system overview

Courtesy: intel

Die Architecture

Courtesy: intel

Voltage and Frequency islands

Courtesy: intel

Package and Test Board

Courtesy: intel

Core & Router Fmax

Courtesy: intel

SCC Platform Board Overview

Courtesy: intel

SCC Software

SCC customized linux Cross compilers for pentium processor

available for c++ & fortran Cross compiled MPI2 including iTAC trace

analyzer available C++ programming frame work ”baremetal C”

availble for creating baremeta apps, OS etc Management Console PC software

sccGui

Courtesy: intel

Programmer's view of SCC

Courtesy: intel

RCCE[2][3] – A small library for many-core communication

Compact light weight communication Research vehicle to see how message passing

APIs map to many cores One can work close to the hardware (eg

manipulate the MPB) Same program executes at all cores Has MPI style APIs & Power mgmt APIs Two level APIs – gory & non gory RCCE emulator

Courtesy: intel

Software Managed Cache Coherence

Implementing hardware managed cache coherence is difficult

Limited Power budget High complexity and validation effort

Software Managed Coherence Scales with number of cores Multiple apps running in separate coherency

domains Dynamically reconfigurable coherency domains Most apps are RO-shared, few RW-shared

Courtesy: intel

Software Managed Cache Coherence (cont)

Shared virtual memory can be used to support coherency (like DSM)

The coherency is maintained by regions being owned exclusively

The regions can then be handed over to other core for exclusive operation

Some regions are jointly acessible No coherence traffic until ownership is changed Consistency guaranteed only at release/acquire

pointsCourtesy: intel

Separated Coherency Domains

Courtesy: intel

Multiple SCC Chips – Wider Coherency

Courtesy: intel

References

[1] J. Howard et al., “A 48-core IA-32 message-passing processor withDVFS in 45nm CMOS,” in Solid-State Circuits Conference Digest ofTechnical Papers (ISSCC), 2010 IEEE International, 7-11 2010, pp. 108–109.

[2] T. G. Mattson and R. F. V. der Wijngaart, “Rcce: a small library formany-core communication,” Intel Corporation, Tech. Rep., May 2010.

[3] T. G. Mattson, M. Riepen, T. Lehnig, P. Brett, W. Haas, P. Kennedy,J. Howard, S. Vangal, N. Borkar, G. Ruhl, and S. Dighe, “The 48-corescc processor: the programmer’s view,” in Proceedings of the 2010ACM/IEEE International Conference for High Performance Computing,Networking, Storage and Analysis, ser. SC ’10. Washington, DC,USA: IEEE Computer Society, 2010, pp. 1–11. [Online]. Available:http://dx.doi.org/10.1109/SC.2010.53