Re: [PATCH] token based thrashing control

[Nikita Danilov <Nikita@Clusterfs.COM>]

Rik van Riel writes:
 > 	
 > The following experimental patch implements token based thrashing
 > protection, using the algorithm described in:
 > 
 > 	http://www.cs.wm.edu/~sjiang/token.htm
 > 
 > When there are pageins going on, a task can grab a token, that
 > protects the task from pageout (except by itself) until it is
 > no longer doing heavy pageins, or until the maximum hold time
 > of the token is over.
 > 
 > If the maximum hold time is exceeded, the task isn't eligable
 > to hold the token for a while more, since it wasn't doing it
 > much good anyway.

[...]

 > --- linux-2.6.7/mm/filemap.c.token	2004-07-30 13:22:28.000000000 -0400
 > +++ linux-2.6.7/mm/filemap.c	2004-07-30 13:22:29.000000000 -0400
 > @@ -1195,6 +1195,7 @@
 >  	 * effect.
 >  	 */
 >  	error = page_cache_read(file, pgoff);
 > +	grab_swap_token();

Token functions are declared to be no-ops if !CONFIG_SWAP, but here
token is used for file-system backed page-fault.

 >  

Nikita.
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