Maximum number of page I/O requests that can be queued by the paging system. This number is divided by 4 to get the actual maximum used by the paging system. It is used to throttle the number of requests as well as to control process swapping.
1 to 1024
The maximum number of I/O requests from the pager is limited by the size of a list of request buffers, which is currently sized at 256.
When the system is subject to bursts of severe memory pressure. A larger value here helps to recover faster from the pressure if more than one swap device is configured or the swap device is a striped device.