Hybrid memory with associative cache
First Claim
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1. A device, comprising:
- a primary memory comprising a host memory space arranged as memory sectors corresponding to host logical block addresses (LBAs);
a secondary memory implemented as a cache for the primary host memory;
a hybrid controller configured to;
receive incoming memory access requests from a host processor and to manage outgoing memory access requests routed to the secondary memory;
receive the incoming memory access requests from the host processor, the incoming memory access requests including a range of LBAs;
route the incoming memory access requests to a set of incoming queues by implementing a priority scheme, the set of incoming queues comprising an incoming execute queue, the priority scheme comprising;
routing invalidate requests in an invalidate ready queue to the execute queue as a highest priority;
routing read requests in a read ready queue to the execute queue as a second highest priority; and
routing promotion requests in a promotion ready queue as a third highest priority;
directly map clusters of host LBAs to clusters of secondary memory, the secondary memory clusters corresponding to a memory space of the cache, the mapping of the host LBA clusters to the secondary memory clusters being fully associative wherein any host LBA cluster can be mapped to any secondary memory cluster;
responsive to a promotion request that specifies a cluster aligned host LBA range, use the mapping of the host LBA clusters to the cache clusters to determine if the host LBA range corresponds to one or more overlapped cache clusters present in the secondary memory;
if the host LBA range corresponds to the one or more overlapped cache clusters, create a bitmap of the overlapped cache clusters; and
implement a write operation to the secondary memory using the bitmap to skip writing the overlapped cache clusters to the secondary memory.
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Abstract
A hybrid memory system includes a primary memory comprising a host memory space arranged as memory sectors corresponding to host logical block addresses (host LBAs). A secondary memory is implemented as a cache for the primary host memory. A hybrid controller is configured directly map the clusters of host LBAs to clusters of secondary memory. The secondary memory clusters correspond to a memory space of the cache. Mapping of the host LBA secondary memory clusters is fully associative such that any host LBA cluster can be mapped to any secondary memory cluster.
79 Citations
19 Claims
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1. A device, comprising:
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a primary memory comprising a host memory space arranged as memory sectors corresponding to host logical block addresses (LBAs); a secondary memory implemented as a cache for the primary host memory; a hybrid controller configured to; receive incoming memory access requests from a host processor and to manage outgoing memory access requests routed to the secondary memory; receive the incoming memory access requests from the host processor, the incoming memory access requests including a range of LBAs; route the incoming memory access requests to a set of incoming queues by implementing a priority scheme, the set of incoming queues comprising an incoming execute queue, the priority scheme comprising; routing invalidate requests in an invalidate ready queue to the execute queue as a highest priority; routing read requests in a read ready queue to the execute queue as a second highest priority; and routing promotion requests in a promotion ready queue as a third highest priority; directly map clusters of host LBAs to clusters of secondary memory, the secondary memory clusters corresponding to a memory space of the cache, the mapping of the host LBA clusters to the secondary memory clusters being fully associative wherein any host LBA cluster can be mapped to any secondary memory cluster; responsive to a promotion request that specifies a cluster aligned host LBA range, use the mapping of the host LBA clusters to the cache clusters to determine if the host LBA range corresponds to one or more overlapped cache clusters present in the secondary memory; if the host LBA range corresponds to the one or more overlapped cache clusters, create a bitmap of the overlapped cache clusters; and implement a write operation to the secondary memory using the bitmap to skip writing the overlapped cache clusters to the secondary memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method, comprising:
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receiving incoming memory access requests from a host processor, the incoming memory access requests including a range of host logical block addresses (LBAs) corresponding to a host LBA space to cache clusters, the host LBA space corresponding to a memory space of a primary memory and the cache clusters corresponding to memory space of a secondary memory arranged to operate as a fully associative cache for the primary memory, wherein any host LBA cluster can be mapped to any cache cluster; routing the incoming memory access requests to a set of incoming queues by implementing a priority scheme, the set of incoming queues comprising an incoming execute queue, the priority scheme comprising; routing invalidate requests in an invalidate ready queue to the execute queue as a highest priority; routing read requests in a read ready queue to the execute queue as a second highest priority; and routing promotion requests in a promotion ready queue as a third highest priority; directly mapping the clusters of LBA to cache clusters responsive to a promotion request that specifies a cluster aligned host LBA range, using the mapping of the host LBA clusters to the cache clusters to determine if the host LBA range corresponds to one or more overlapped cache clusters present in the secondary memory; and if the host LBA range corresponds to the one or more overlapped cache clusters, creating a bitmap of the overlapped cache clusters; and implementing a write operation to the secondary memory using the bitmap to skip writing the overlapped cache clusters to the secondary memory. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A controller system for a hybrid memory system, the controller comprising:
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a hybrid controller configured data transfers between the host processor and a flash memory, the flash memory configured to serve as a cache for a magnetic disk, the hybrid controller comprising; a flash control and transfer management (FCTM) layer configured to; receive incoming memory access requests from a host processor and to manage outgoing memory access requests routed to the cache; receive the incoming memory access requests from the host processor, the incoming memory access requests including a range of LBAs; route the incoming memory access requests to a set of incoming queues by implementing a priority scheme, the set of incoming queues comprising an incoming execute queue, the priority scheme comprising; routing invalidate requests in a invalidate ready queue to the execute queue as a highest priority; routing read requests in a read ready queue to the execute queue as a second highest priority; and routing promotion requests in a promotion ready queue as a third highest priority; directly map clusters of host logical block addresses (LBAs) corresponding to a host LBA space to cache clusters, the host LBA space corresponding to a memory space of a primary memory and the cache clusters corresponding to memory space of a secondary memory arranged to operate as a fully associative cache for the primary memory, wherein any host LBA cluster can be mapped to any cache cluster; responsive to a promotion request that specifies a cluster aligned host LBA range, use the mapping of the host LBA clusters to the cache clusters to determine if the host LBA range corresponds to one or more overlapped cache clusters present in the secondary memory; and if the host LBA range corresponds to the one or more overlapped cache clusters, create a bitmap of the overlapped cache clusters; and implement a write operation to the secondary memory using the bitmap to skip writing the overlapped cache clusters to the secondary memory. - View Dependent Claims (18, 19)
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Specification