Managing I/O operations in multi-core systems

A system for managing I/O operations in data storage systems having one or more multi-core processors, the system configured to:

• maintain a first variable configured to simultaneously store a first value and a second value, the first value storing a counter associated with a number of I/O operations directed to a storage object that remain outstanding, and the second value storing a gate bit associated with an open or closed gate condition, wherein the first variable is stored in a shared memory location accessible by two or more cores of the one or more multi-core processors;
• track I/O operations directed to a storage object, wherein tracking includes incrementing the first value of the first variable when an I/O operation is received and decrementing the first value of the first variable when an I/O operation is processed;
• determine that the storage object needs to perform an operation that requires the storage object to change state;
• set the second value, wherein the bit location associated with the gate bit of the first variable is set to a value indicative of a gate closed condition such that subsequent I/O operations are queued in a respective core of the one or more multi-core processors;
• drain outstanding I/O operations by continuing to process I/O operations until the first value of the first variable reaches zero;
• perform operations that required the storage object to change state;
• and
• clear the gate bit, wherein the bit location associated with the gate bit of the first variable is set to a value indicative of a gate open condition such that subsequent I/O are no longer queued.

A computer program product including non-transitory computer readable storage medium having stored thereon computer executable instructions that when executed by the multi-core processor of a computer perform steps comprising:

• maintaining a first variable configured to simultaneously store a first value and a second value, the first value storing a counter associated with a number of I/O operations directed to a storage object that remain outstanding, and the second value storing a gate bit associated with an open or closed gate condition, wherein the first variable is stored in a shared memory location accessible by two or more cores of the one or more multi-core processors;
• tracking I/O operations directed to a storage object, wherein tracking includes incrementing the first value of the first variable when an I/O operation is received and decrementing the first value of the first variable when an I/O operation is processed;
• determining that the storage object needs to perform an operation that requires the storage object to change state;
• setting the second value, wherein the bit location associated with the gate bit of the first variable is set to a value indicative of a gate closed condition such that subsequent I/O operations are queued in a respective core of the one or more multi-core processors;
• draining outstanding I/O operations by continuing to process I/O operations until the first value of the first variable reaches zero;
• performing operations that required the storage object to change state;
• and
• clearing the gate, wherein the bit location associated with the gate bit of the first variable is set to a value indicative of a gate open condition such that subsequent I/O are no longer queued.