Subject: kern/35741: PDPOLICY_CLOCKPRO has no tuning parameters analogous to vm.filemax, etc.
To: None <kern-bug-people@netbsd.org, gnats-admin@netbsd.org,>
From: None <blair.sadewitz@gmail.com>
List: netbsd-bugs
Date: 02/20/2007 18:20:00
>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?