Systems and methods for scheduling write requests for a solid state storage device

摘要

An I/O scheduler can manage and schedule write requests that are sent to a storage device in order to prevent the write requests from dominating a storage buffer of the storage device. The I/O scheduler can monitor the number of I/O requests in the storage buffer and maintain a balance between write requests and read requests in the storage buffer. The I/O scheduler monitor the latency of the storage device in processing write requests and manage the write requests sent to the storage device based on the latency. The I/O scheduler can utilize one or more write thresholds. The write thresholds can define thresholds of the number of write requests in the storage buffer and thresholds for the latency of the storage device in processing write requests. The write threshold can represent acceptable levels of write request in the storage buffer and acceptable latency for write requests.

主权项

1. A non-transitory computer readable storage medium having stored thereon instructions that when executed by one or more computing systems cause the one or more computing systems to:
identify a write request to be sent to a storage device; determine, from a first counter, that a read request is being held in a first cache waiting to be sent to the storage device; determine, from a second counter, a number of read requests that are being held in a buffer of the storage device; determine, from a third counter, a number of write requests that are being held in the buffer of the storage device; determine a first percentage of write requests among a total of the number of read requests and the number of the write requests that are being held in the buffer of the storage device; compare the first percentage to a first threshold; in response to the first percentage being less than or equal to the first threshold,
send the write request to the storage device; and in response to the first percentage being greater than the first threshold,
hold the write request in a second cache for sending to the storage device at a later time.