Re: VM: Where do we stand?

[Daniel Phillips <phillips@bonn-fries.net>]

On January 23, 2002 10:32 am, Duraid Madina wrote:
> >The paging queues ( determing the age of the page and whether to 
> >free or clean it) need to be written... the algorithms being used
> >are terrible.
> >
> > * For the nominal page scan, it is using a one-hand clock algorithm.  
> >   All I can say is:  Oh my god!  Are they nuts?  That was abandoned
> >   a decade ago.

We don't use a one-hand clock now, we use an lru list coupled with a virtual 
scan which sucks slightly less, but only slightly.

> > The priority mechanism they've implemented is nearly
> >   useless.

There's a new priority mechanism now ;-)

> > * To locate pages to swap out, it takes a pass through the task list. 
> >   Ostensibly it locates the task with the largest RSS to then try to
> >   swap pages out from rather then select pages that are not in use.
> >   From my read of the code, it also botches this badly.

It now tries to select pages that are not in use.

--
Daniel