Re: [PLUG] swappiness and ssd

["K.S. Bhaskar" <bhaskar@bhaskars.com>]

I wanted to report on my experiments with swappiness (you really have to run with something like this for a while before you can conclude anything).  Swappiness of 80 seems to be a sweet spot for my laptop with an SSD, using a swap file located on a /home partition which is itself encrypted using dm-crypt.

-- Bhaskar

On Thu, Apr 16, 2015 at 10:01 AM, K.S. Bhaskar <bhaskar@bhaskars.com> wrote:

The default swappiness on Ubuntu systems is 60, and presumably takes into consideration the relative performance of writes to and reads from the swap file / partition.  The ratio of write performance to read performance would be higher for SSDs than rotating media, since SSD reads are truly random whereas writes are in pages (in rotating media, seek and latency times would tend to apply to both).  Therefore, it seems to me that if swap is located on SSD, we should increase swappiness, to encourage less frequently used pages to be written out, since they can be brought back in very fast when needed.  Does that seem reasonable or am I missing something?  Thanks.

Regards

-- Bhaskar

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