Accession Number:

ADA181572

Title:

On-Chip Instruction Caches for High Performance Processors,

Descriptive Note:

Corporate Author:

STANFORD UNIV CA COMPUTER SYSTEMS LAB

Report Date:

1987-01-01

Pagination or Media Count:

12.0

Abstract:

Continued increases in clock rates of VLSI processors demand a reduction in the frequency of expensive off-chip memory references. Without such a reduction, the chip crossing time and the constraints of external logic will severely impact the clock cycle. By absorbing a large fraction of instruction references, on-chip caches substantially reduce off-chip communication. Minimizing the average instruction access time with a limited silicon budget requires careful analysis of both cache architecture and implementation. This paper examines some important design issues and tradeoffs that maximize the performance of on-chip instruction caches, while retaining implementation ease. Our discussion focuses on the instruction cache design for MIPS-X, a pipelined, 32-bit, reduced instruction set, 20 MIPS peak, CMOS processor designed at Stanford. The on-chip instruction cache is 2K bytes and allows single-cycle instruction accesses. Trace driven simulations show that the cache has an average miss rate of 12 percent resulting in an average instruction access time of 1.24 cycles. Reprints.

Subject Categories:

  • Computer Systems

Distribution Statement:

APPROVED FOR PUBLIC RELEASE