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Date: Wed, 21 Apr 2004 18:40:09 -0700 (PDT)
From: Matthew Dillon <dillon@apollo.backplane.com>
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To: Julian Elischer <julian@elischer.org>
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cc: hackers@freebsd.org
cc: Stephan Uphoff <ups@tree.com>
Subject: Re: how to flush out cache.? 
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:Actually what I'm looking for is 
:"throw away clean data"
:
:I want to dump the cached version of a file so that I can force a reread
:of the disk.

    MS_INVALIDATE doesn't do that.  

    madvise()'s MADV_FREE does what you want, BUT it does not currently 
    work (at least on 4.x or in DFly) on file-backed data, it only works
    with anonymous memory.  I believe that on some systems MADV_FREE does
    what you expect, e.g. like on Solaris (though I am not 100% sure), so
    it would not be far-fetched to go and implement it.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>