From owner-freebsd-current@FreeBSD.ORG  Wed Feb 16 23:13:47 2005
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Date: Wed, 16 Feb 2005 15:13:46 -0800
From: Julian Elischer <julian@elischer.org>
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To: Brooks Davis <brooks@one-eyed-alien.net>
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cc: Eric Anderson <anderson@centtech.com>
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Subject: Re: where did all my memory go? (file system cache)
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slightly off topic but..

Brooks Davis wrote:

>On Wed, Feb 16, 2005 at 01:13:13PM -0800, Sean McNeil wrote:
>  
>
>The concept that most of your memory should be entierly free when the
>system is not under load is simply wrong.  The simplistic world view of
>memory being allocated to a specific task or entierly free simply isn't
>correct for all that it makes for nice graphs anyone can pretend they
>understand.  You can produce some sort of aproximation of the output you
>see on other systems by modifying the program to include inactive memory
>in free memory.  That's what I did with Ganglia.
>

what I really want is a way to FORce certain pages out of cache.
In particular I need to verify teh correctness of the version on 2ndary 
storage..

what I want is:

int fd = open("myfile",...);
write1GBfiletodisk(fd, data);
ioctl(fd, PURGEFROMCACHE);
perform_md5(fd);

and be sure that teh MD5 is that of what is on the disk.
not what is in RAM.

>
>-- Brooks
>
>  
>