Re: Swappiness default

On 05/23/2011 10:51 AM, Hakan Koseoglu wrote:

Setting the swappiness to 0 delays any swaps until you've run out of
RAM completely and only then it starts writing to disk. As a result if
you have a lot of RAM, it's preferrable. On the other hand, when you
run out of memory, it will start heavily swapping immediately (depends
on how many processes want to grab the lot).

If you set it to a high number, the system will housekeep very often
and you will experience slow downs when you really don't need any (I
have 2GB free, why are you swapping 1GB, oh the wise kernel?)...


Because using ram to cache frequently accessed files (such as mem-mapped libraries, as an example) is much better for overall system performance than holding little used pages of application ram. Course, if you have objective benchmarks that contradict this...... (yeah, I know, I'm not providing any either. But without proof otherwise, I'm going with the opinion of those who actually performance test the kernel with measurable metrics)

You should also keep in mind that a page is swap can also be in Ram at the same time. Being in swap only means that that ram can be quickly paged out instantly at need. Again, overall better system speed is achieved.



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