Prefetch manager

Prefetch manager manages asynchronous reads of prefetched pages. sp_iqsysmon generates main (Table A-7) and temporary (Table A-8) prefetch manager statistics. Statistic names are sorted alphabetically.

**Table A-7: Prefetch manager main statistics**
PFMgrCondVar	PFMgrNDropped
PFMgrNRead	PFMgrNReading
PFMgrNSubmitted	PFMgrNThreads
PFMgrNValid

**Table A-8: Prefetch manager temporary statistics**
PFMgrCondVar	PFMgrNDropped
PFMgrNRead	PFMgrNReading
PFMgrNSubmitted	PFMgrNThreads
PFMgrNValid