Dell Products Inc.

Steve Ivester

Kaustubh Sahasrabudhe

John Creed

A multi-node storage system uses local mutual exclusion to perform fabricless local memory access and non-local mutual exclusion to perform memory access via an inter-nodal fabric. A local access mode bit and remote access request flag are associated with each data slot and its associated metadata in shared memory of the storage system. Local mutual exclusion such as a Peterson Lock is used to avoid conflict between local IO threads when the local access mode is set and the remote access request flag is not set. A remote IO thread that determines that the local access mode bit for a target slot is set will set the remote access flag. In response, a local IO thread that obtains the Peterson Lock will unset the local access mode bit and release the Peterson Lock, thereby enabling remote access to the slot and its metadata by the remote IO thread. The remote access request flag is cleared and the local access mode enabled after the remote access is completed.

Atomic CPU access to shared metadata in a fabric-attached multi-node array with shared memory

Worker threads allocate at least some recycled cache slots of a local portion of a shared memory to the compute node to which the memory portion is local. More specifically, the recycled cache slots are allocated prior to receipt of the IO that the recycled cache slot will be used to service. The allocated recycled cache slots are added to primary queues of each compute node. If a primary queue is full then the worker thread adds the recycled cache slot, unallocated, to a secondary queue. Cache slots in the secondary queue can be claimed by any compute node associated with the shared memory. Cache slots in the primary queue can be used by the local compute node without sending test and set messages via the fabric that interconnects the compute nodes, thereby improving IO latency.

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Grafton, MA, United States of America

Steve Ivester