>Number:         35741
>Category:       kern
>Synopsis:       PDPOLICY_CLOCKPRO has no tuning parameters analogous to vm.filemax, etc.
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 20 18:20:00 +0000 2007
>Originator:     Blair Sadewitz
>Release:        4.99.10/amd64
>Organization:
>Environment:
NetBSD dexamyl 4.99.12 NetBSD 4.99.12 (DEXAMYL) #3: Mon Feb 19 18:37:01 EST 2007  blair@dexamyl:/home/blair/build/obj/sys/arch/amd64/compile/DEXAMYL amd64

>Description:
PDPOLICY_CLOCKPRO is clearly a superior page replacement policy.  However, for workloads that involve, for instance, a lot of anonymous/exec memory and don't need a lot of file cache, the system starts swapping out pages to disk like mad.  Presumably, with heavy disk I/O, file pages become 'hotter' than anon/exec pages for running applications.  This can cause a "desktop" environment such as KDE or GNOME to slow to a virtual standstill in the face of relentless swapping.
>How-To-Repeat:
Build a kernel with PDPOLICY_CLOCKPRO, start a lot of bloated applications, then do a lot of disk I/O.  I have had two others confirm this problem.
>Fix:
Not sure at all.  Add "weighting" to items in listq?