where did all my memory go? (file system cache)

[Julian Elischer]

Joseph Koshy wrote:

>>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.
>>    
>>
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>unmount(file-system-of("myfile")) (even if it fails) ?
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I actually heard this trick before.. I can't say I'm enthusiastic about it..
it also forces the flushing of a lot of stuff I may not want to flush, (yet)
I don't want to force my other apps to have to reload their cached data.

Neat trick though.

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