A multi-processor system with cache sharing has a plurality of processor sub-systems and a cache coherence interconnect circuit. The processor sub-systems have a first processor sub-system and a second processor sub-system. The first processor sub-system includes at least one first processor and a first cache coupled to the at least one first processor. The second processor sub-system includes at least one second processor and a second cache coupled to the at least one second processor. The cache coherence interconnect circuit is coupled to the processor sub-systems, and used to obtain a cache line data from an evicted cache line in the first cache, and transfer the obtained cache line data to the second cache for storage.

Systems and methods are directed to selectively bypassing allocation of cache lines in a cache. A bypass predictor table is provided with reuse counters to track reuse characteristics of cache lines, based on memory regions to which the cache lines belong in memory. A contender reuse counter provides an indication of a likelihood of reuse of a contender cache line in the cache pursuant to a miss in the cache for the contender cache line, and a victim reuse counter provides an indication of a likelihood of reuse for a victim cache line that will be evicted if the contender cache line is allocated in the cache. A decision whether to allocate the contender cache line in the cache or bypass allocation of the contender cache line in the cache is based on the contender reuse counter value and the victim reuse counter value.

Systems and methods are directed to selectively bypassing allocation of cache lines in a cache. A bypass predictor table is provided with reuse counters to track reuse characteristics of cache lines, based on memory regions to which the cache lines belong in memory. A contender reuse counter provides an indication of a likelihood of reuse of a contender cache line in the cache pursuant to a miss in the cache for the contender cache line, and a victim reuse counter provides an indication of a likelihood of reuse for a victim cache line that will be evicted if the contender cache line is allocated in the cache. A decision whether to allocate the contender cache line in the cache or bypass allocation of the contender cache line in the cache is based on the contender reuse counter value and the victim reuse counter value.

Systems and methods relate to cost-aware cache management policies. In a cost-aware least recently used (LRU) replacement policy, temporal locality as well as miss cost is taken into account in selecting a cache line for replacement, wherein the miss cost is based on an associated operation type including instruction cache read, data cache read, data cache write, prefetch, and write back. In a cost-aware dynamic re-reference interval prediction (DRRIP) based cache management policy, miss costs associated with operation types pertaining to a cache line are considered for assigning re-reference interval prediction values (RRPV) for inserting the cache line, pursuant to a cache miss and for updating the RRPV upon a hit for the cache line. The operation types comprise instruction cache access, data cache access, prefetch, and write back. These policies improve victim selection, while minimizing cache thrashing and scans.

Disclosed herein is an apparatus and method for controlling level 0 caches, capable of delivering data to a processor without errors and storing error-free data in the caches even when soft errors occur in the processor and caches. The apparatus includes: a level 0 cache #0 connected to the load/store unit of a first processor; a level 0 cache #1 connected to the load/store unit of a second processor; and a fault detection and recovery unit for reading from and writing to tag memory, data memory, and valid bit memory of the level 0 cache #0 and the level 0 cache #1, performing the write-back and flush of the level 0 cache #0 and the level 0 cache #1 based on information stored therein, and instructing the load/store units of the first and second processors to stall a pipeline and to restart an instruction #n.

Disclosed herein is an apparatus and method for controlling level 0 caches, capable of delivering data to a processor without errors and storing error-free data in the caches even when soft errors occur in the processor and caches. The apparatus includes: a level 0 cache #0 connected to the load/store unit of a first processor; a level 0 cache #1 connected to the load/store unit of a second processor; and a fault detection and recovery unit for reading from and writing to tag memory, data memory, and valid bit memory of the level 0 cache #0 and the level 0 cache #1, performing the write-back and flush of the level 0 cache #0 and the level 0 cache #1 based on information stored therein, and instructing the load/store units of the first and second processors to stall a pipeline and to restart an instruction #n.

A method includes storing a first block of main memory in a cache line of a direct-mapped cache, storing a first tag in a current tag field of the cache line, wherein the first tag identifies a first memory address for the first block of main memory, and storing a second tag in a previous miss tag field of the cache line in response to receiving a memory reference having a tag that does not match the tag stored in the current tag field. The second tag identifies a second memory address for a second block of main memory, and the first and second blocks are both mapped to the cache line. The method may further include storing a binary value in a last reference bit field to indicate whether the most recently received memory reference was directed to the current tag field or previous miss tag field.

Various embodiments for grouping tracks for destaging by a processor device in a computing environment are provided. Tracks are selected for destaging from a least recently used (LRU) list and the selected tracks are moved to a destaging wait list. One of the selected tracks is selected from the destaging wait list and the selected tracks are grouped for destaging. A first track and a last track are located from the group of selected tracks of the destaging wait list. The destaging is commenced from the first track in the group of selected tracks. A track is added to the group of selected tracks if the track is one of modified and located in a cache, otherwise, a next one of the selected tracks in the group of selected tracks is moved to.

Various embodiments for grouping tracks for destaging by a processor device in a computing environment are provided. Tracks are selected for destaging from a least recently used (LRU) list and the selected tracks are moved to a destaging wait list. One of the selected tracks is selected from the destaging wait list and the selected tracks are grouped for destaging. A first track and a last track are located from the group of selected tracks of the destaging wait list. The destaging is commenced from the first track in the group of selected tracks. A track is added to the group of selected tracks if the track is one of modified and located in a cache, otherwise, a next one of the selected tracks in the group of selected tracks is moved to.

Example implementations relate to storing memory erasure information in memory devices on a memory module. In example implementations, a memory location associated with an error in a first cache line may be identified. The first cache line may include data read from the memory location, and the memory location may be in a first memory device of a plurality of memory devices on a memory module. A device number corresponding to the first memory device may be written to one of the plurality of memory devices. When the memory location is read for a second cache line, the device number corresponding to the first memory device may be retrieved. The second cache line may include the retrieved device number and data read from the memory location.