Emc IP Holding Company LLC

Sichao Zhu

Jaeyoo Jung

Arieh Don

Owen Martin

Krishna Deepak Nuthakki

Benjamin Randolph

Raghuram Adabala

Dharmesh J Desai

Techniques for processing I/O operations may include: receiving an I/O operation directed to a logical device having an associated service level objective with a target I/O response time; performing first processing that determines an estimated response time for the I/O operation, and determining, based on the estimated response time for the I/O operation and the associated service level objective, whether to delay the I/O operation by an additional amount of time thereby increasing a measured response time for the I/O operation by the additional amount. The first processing may include determining a fixed baseline amount of time for the I/O operation; determining a cumulative amount of time estimated to service pending I/O operation queued for service prior to the I/O operation; and determining an expected service time estimated for servicing the I/O operation. Moving averages maintained for different I/O types and sizes may be used in determining I/O service times.

SLO I/O delay prediction

Techniques for processing I/O operations may include: receiving an I/O having an associated expected execution time (EET) and I/O service level; selecting, in accordance with the EET and service level of the I/O, a first I/O queue from multiple pending I/O queues; inserting the I/O into the first I/O queue; and performing I/O shifting. I/O shifting may include shifting I/Os from one pending I/O queue to another that is ranked immediately higher than the one pending I/O queue. The multiple I/O queues may be ranked from a highest priority queue to a lowest priority queue. I/O shifting may shift I/Os from the highest priority queue to execution and shifting I/Os from another queue into the highest priority queue. I/O shifting is subject to remaining credits available of the multiple I/O queues and time distance between source and target queues.

Multi-level time decay storage queue

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Sichao Zhu