linux-kernel - Simple Code change suggestion : pdflush() : clean pages in 1/2 time

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Date:	Wed, 8 Jul 2009 13:03:28 -0700
From:	Mitchell Erblich <erblichs@...thlink.net>
To:	linux-kernel@...r.kernel.org
Subject: Simple Code change suggestion : pdflush() : clean pages in 1/2 time

Group,

	pdflush threads clean dirty pages.

	Under the past simple assumption that a greater number of
	  page daemon threads will have the TENDENCY to clean
	  the pages faster.

	  A simple change is to create 2x the number of threads
	  within the same timeframe as before.
	
	   Thus, in mm/pdflush.c _pdflush() thread creation is done
	    in 1/2 HZ. ( "/" or ">>" , compiler will optimize)
	    Above 1 sec omment should also be changed.

	   IMO, We could do in 1/4 or 1/8 HZ,  but load (backlog of dirty  
pages)
	   should then be tracked and watermarks set and determine whether
	  keep adding  additional threads allows us to clean the pages faster.
	  (Yes, did that / done that and the code is/was ... too complicated)

	  The 2nd part is to prevent thread creation / destruction thrashing,
	  keep around the extra threads to handle the bursts of frees so HZ
	  is still kept to limit exit rate.

	Mitchell Erblich
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