Method and apparatus for software-based dispatch stall mechanism for scoreboarded IOPs
US6345356B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 16, 1999 |
| Grant date | Feb 5, 2002 |
| Priority date | — |
| Expiry date | Jul 16, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3858
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A dummy instruction is issued, followed by several groups of No Operations (NOPs). The instruction sequencer unit (ISU) detects the dummy instruction and stalls the pipeline until the scoreboard indicates the XER count is valid. After a read from a scoreboarded Special Purpose Register (SPR), No Operation—Internal Operations (NOP—IOPs) are inserted between write and read SPR IOPs to allow an ISU scoreboard mechanism to be activated before being tested by a read SPR IOP. A read-write-read sequence is utilized: a dummy read of the string count field from a scoreboarded SPR, writing that value back to the same SPR and then performing a read of the SPR once again. A predetermined number of dummy IOPs follow the initial dummy read to prevent the value of the string count field from being read too soon.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.