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I've seen sysadmins playing with /proc/sys/vm/drop_caches (echo 3 into this file from a cron) in order to free caches. Is there a real interrest in doing this? Aren't the clean caches reclaimed when needed?


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migrated from Feb 24 '12 at 6:25

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In normal operation it's not necessary. The normal reason for doing it is to be able to test the performance of some program when it is running with a cold cache.

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To add, having the caches freed periodically can actually hurt system performance, since often-used files will have to be read from disk again and again. Essentially, free memory is wasted memory (if the caching is implemented correctly). – grawity Feb 21 '12 at 15:42

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