Read Starvation

As IO schedule insert requests in ascending sequence as they come in, read to latter block may be kept waiting in the queue for a long time.  The problem can be further deteriorated by writes which batch up several requests and flushes to the disk periodically.  This is called writes-starving-read problem.

IO scheduler is further optimized to address this issue.  In Linux 2.4 kernel, the Linux Elevator scheduler will stop inserting new requests when the list have sufficient number of old request to process.  The algorithm is simple and it could help in some situations.