Universal cache management system

One or more non-transitory computer-readable media storing one or more sequences of instructions which, when executed by one or more processors, causes:

• allocating, in volatile memory of a first computing device, a first cache exclusively to a first instance of two or more data-processing instances, wherein the first cache is configured to store copies of a first set of data blocks that are persistently stored on one or more storage devices, and wherein the allocating the first cache is performed, at least in part, by an operating system (OS) instance;
• allocating, in the same volatile memory of the first computing device, a second cache exclusively to a second instance of the two or more data-processing instances, wherein the second cache is configured to store copies of a second set of data blocks that are persistently stored on the one or more storage devices, and wherein the allocating the second cache is performed, at least in part, by the OS instance;
• allocating at least a portion of a common cache in the same volatile memory of the first computing device, wherein the allocating at least a portion of the common cache is performed, at least in part, by the OS instance;
• the first instance performing:
• identifying for eviction from the first cache a first data block at least because the first data block has not been changed since the first data block was last persistently written to the one or more storage devices;
• in response to identifying for eviction from the first cache a first data block at least because the first data block has not been changed since the first data block was last persistently written to the one or more storage devices:
• causing the first data block to be stored in the common cache, and
• removing the first data block from the first cache;
• and
• the second instance performing:
• identifying for eviction from the second cache a second data block at least because the second data block has not been changed since the second data block was last persistently written to the one or more storage devices:
• in response to identifying for eviction from the second cache a second data block at least because the second data block has not been changed since the second data block was last persistently written to the one or more storage devices:
• causing the second data block to be stored in the common cache, and
• removing the second data block from the second cache;
• maintaining data blocks, including the first data block and the second data block, in the common cache without persistently writing the data blocks to the one or more storage devices.