[CentOS] Effectiveness of CentOS vm.swappiness

[Greg Lindahl]

On Fri, Jun 05, 2015 at 09:33:11AM -0700, Gordon Messmer wrote:
> On 06/05/2015 03:29 AM, Markus "Shorty" Uckelmann wrote:
> >some (probably unused) parts are swapped out. But, some of
> >those parts are the salt-minion, php-fpm or mysqld. All services which
> >are important for us and which suffer badly from being swapped out.
> 
> Those two things can't really both be true.  If the pages swapped
> out are unused, then the application won't suffer as a result.

No.

Let's say the application only uses the page once per hour. If there
is also I/O going on, then it's easy to see that the kernel could
decide to page the page out after 50 minutes, leaving the application
having to page it back in 10 minutes later.

-- greg