发明授权
US5802575A Hit bit for indicating whether load buffer entries will hit a cache when
they reach buffer head
失效
命中位用于指示加载缓冲区条目到达缓冲区头时是否会到达高速缓存
- 专利标题: Hit bit for indicating whether load buffer entries will hit a cache when they reach buffer head
- 专利标题(中): 命中位用于指示加载缓冲区条目到达缓冲区头时是否会到达高速缓存
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申请号: US946611申请日: 1997-10-07
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公开(公告)号: US5802575A公开(公告)日: 1998-09-01
- 发明人: Dale Greenley , Leslie Kohn , Ming Yeh , Greg Williams
- 申请人: Dale Greenley , Leslie Kohn , Ming Yeh , Greg Williams
- 申请人地址: CA Palo Alto
- 专利权人: Sun Microsystems, Inc.
- 当前专利权人: Sun Microsystems, Inc.
- 当前专利权人地址: CA Palo Alto
- 主分类号: G06F9/312
- IPC分类号: G06F9/312 ; G06F9/38 ; G06F12/08 ; G06F12/00
摘要:
A dual-ported tag array of a cache allows simultaneous access of the tag array by miss data of older LOAD instructions being returned during the same cycle that a new LOAD instruction is accessing the tag array to check for a cache hit. Because a load buffer queues LOAD instructions, the cache tags for older LOAD instructions which missed the cache return later when new LOAD instructions are accessing a tag array to check for cache hits. A method and apparatus for calculating and maintaining a hit bit in a load buffer perform the determination of whether or not a newly dispatched LOAD will hit the cache after it has been queued into the load buffer and waited for all older LOADs to be processed. A load buffer data entry includes the hit bit and all information necessary to process the LOAD instruction and calculate the hit bits for future LOAD instructions which must be buffered. A method and apparatus for servicing LOAD instructions, in which the access of the data array portion of a cache and the tag array portion are decoupled, allows the delayed access of the data array after a LOAD has been delayed in the load buffer without reaccessing the tag array.
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