How to Clear Memory Cache on Linux

I am well aware this is not a technical forum but one aspect of this writing troubles me. While there may be circumstances when the system cache should be cleared (testing purposes mainly), I can't see why would one do this in a cron job, because it obviously results in huge performance drop, nearly insulting to all the work that has been done to maximize performance.

Also, drop_caches should be reset back to zero after testing. I could not find any info whether setting drop_caches to 3 only clears the cache, or whether it clears and disables it altogether. Any knowledgeable forum reader ? Thx.

Writing to drop_caches is a single-shot action, and then the cache starts re-filling. There are other tunables to alter ongoing behavior of the caching system.

For my own testing, I prefer to just dirty the caches with a single, un-measured run, followed by how ever many measured runs I need, with no cache-clearing in between.