Qualcomm Incorporated

Raghuveer Raghavendra

Gurvinder Singh Chhabra

Richard Senior

Nieyan Geng

Andres Alejandro Oportus Valenzuela

Christopher E Koob

Anand Janakiraman

Christopher Porter

Richard Alan Stewart

Reducing bandwidth consumption when performing free memory list cache maintenance in compressed memory schemes of processor-based systems is disclosed. In this regard, a memory system including a compression circuit is provided. The compression circuit includes a compress circuit that is configured to cache free memory lists using free memory list caches comprising a plurality of buffers. When a number of pointers cached within the free memory list cache falls below a low threshold value, an empty buffer of the plurality of buffers is refilled from a system memory. In some aspects, when a number of pointers of the free memory list cache exceeds a high threshold value, a full buffer of the free memory list cache is emptied to the system memory. In this manner, memory access operations for emptying and refilling the free memory list cache may be minimized.

Reducing bandwidth consumption when performing free memory list cache maintenance in compressed memory schemes of processor-based systems

Reducing metadata size in compressed memory systems of processor-based systems is disclosed. In one aspect, a compressed memory system provides 2compressed data regions, corresponding 2sets of free memory lists, and a metadata circuit. The metadata circuit associates virtual addresses with abbreviated physical addresses, which omit N upper bits of corresponding full physical addresses, of memory blocks of the 2compressed data regions. A compression circuit of the compressed memory system receives a memory access request including a virtual address, and selects one of the 2compressed data regions and one of the 2sets of free memory lists based on a modulus of the virtual address and 2. The compression circuit retrieves an abbreviated physical address corresponding to the virtual address from the metadata circuit, and performs a memory access operation on a memory block associated with the abbreviated physical address in the selected compressed data region.

Reducing metadata size in compressed memory systems of processor-based systems

Aspects disclosed involve reducing or avoiding buffering of evicted cache data from an uncompressed cache memory in a compression memory system when stalled write operations occur. A processor-based system is provided that includes a cache memory and a compression memory system. When a cache entry is evicted from the cache memory, cache data and a virtual address associated with the evicted cache entry are provided to the compression memory system. The compression memory system reads metadata associated with the virtual address of the evicted cache entry to determine the physical address in the compression memory system mapped to the evicted cache entry. If the metadata is not available, the compression memory system stores the evicted cache data at a new, available physical address in the compression memory system without waiting for the metadata. Thus, buffering of the evicted cache data to avoid or reduce stalling write operations is not necessary.

Reducing or avoiding buffering of evicted cache data from an uncompressed cache memory in a compression memory system when stalled write operations occur

Aspects include computing devices, systems, and methods for implementing executing decompression of a compressed page. A computing device may determine a decompression block belonging to a compressed page that contains a code instruction requested in a memory access request. Decompression blocks, other than the decompression block containing the requested code instruction, may be selected for decompression based on their locality with respect to the decompression block containing the requested code instruction. Decompression blocks not identified for decompression may be substituted for a fault or exception code. The computing device may decompress decompression blocks identified for decompression, terminating the decompression of the compressed page upon filling all blocks with decompressed blocks, faults, or exception code. The remaining decompression blocks belonging to the compressed page may be decompressed after or concurrently with the execution of the requested code instruction.

Efficient decompression locality system for demand paging

Aspects include computing devices, systems, and methods for implementing executing decompression of a compressed page. A computing device may determine a decompression block of a compressed page that contains a code instruction requested in a memory access request. Decompression blocks, other than the decompression block containing the requested code instruction, may be selected for decompression based on being situated between an end of the compressed page and the decompression block containing the requested code instruction. Decompression blocks not identified for decompression may be substituted for a fault or exception code. The computing device may decompress decompression blocks identified for decompression, starting at the end of the compressed page and terminating the decompression of the compressed page upon filling all blocks with decompressed blocks, faults, or exception code. The remaining decompression blocks of the compressed page may be decompressed after or concurrently with the execution of the requested code instruction.

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San Diego, CA, United States of America

Raghuveer Raghavendra