Browse Prior Art Database

Meta-Miss for Instruction Lines

IP.com Disclosure Number: IPCOM000101449D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 33K

Publishing Venue

IBM

Related People

Emma, PG: AUTHOR [+5]

Abstract

For a processor which possesses a BHT any advantage associated with resequencing of the doublewords (DWs) associated with an Instruction (I)-Miss can be derived directly from the contents of a BHT.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 96% of the total text.

Meta-Miss for Instruction Lines

       For a processor which possesses a BHT any advantage
associated with resequencing of the doublewords (DWs) associated with
an Instruction (I)-Miss can be derived directly from the contents of
a BHT.

      When a BHT access is found to be missing in the cache, a
determination as to the benefit from a resequencing of the DWs of the
line can be made utilizing the following factor:
    The presence of BHT information about the line missed
      that indicates the presence of intra-line taken
      branches that will delay the processor if the
      doublewords are presented sequentially starting at the
      position of the miss.
The proximity of the decoder to the point of current missing I-Fetch
is not relevant as any advantage in this regard will be lost to the
leading edge of the I-Miss.

      Given the determination that a performance advantage exists for
such an I-Miss, the information needed to resequence the I-Miss can
be derived from the DWI (Double Word Index) of the succession of TA
(Target Addresses) and BA (Branch Addresses) derived from the BHT.
If the intra-line succession of branches is indexed so that the i-th
TA, TAi, is followed by the i+1-th BA, BAi+1, the most direct way to
control the resequencing is to exploit the DWI of these addresses.
The receipt by the memory control of:
   DWI(TA0), DWI(BA1)
   DWI(TA1), DWI(BA2)
instructs the controller to transmit the DWs indicated by t...