Date: Thu, 20 Aug 2020 12:40:32 -0600 From: "@lbutlr" <kremels@kreme.com> To: FreeBSD <freebsd-questions@freebsd.org> Subject: Re: Swapping when memory is idle?? Message-ID: <D2FB0F28-E822-48FF-BCEF-AC023831EDBE@kreme.com> In-Reply-To: <CAAdA2WP8cr-uRgDRT_GX0faCSAFWORn9UMwqLZOWtLgXd0Hc9w@mail.gmail.com> References: <CAAdA2WP8cr-uRgDRT_GX0faCSAFWORn9UMwqLZOWtLgXd0Hc9w@mail.gmail.com>
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On 20 Aug 2020, at 01:53, Odhiambo Washington <odhiambo@gmail.com> = wrote: > I have a machine with 16GB RAM and not heavily used. > I see from `top` some things that I do not understand well. > Why would a system use swap when memory is idle? Efficiency. Rather than reloading from static state disk libraries, you = reload from swapped out RAM. This is faster as the swap maps right to = the RAM and you are not reloading libraries and following depends. An efficient system *may* use swap for any page that is not accessed for = a certain period of time, trying to keep the system with as much memory = as possible, or more usually a specific task will use a lot of memory, = forcing pages to swap. This does not mean that memory was mixed out nor = does it mean you need more RAM. Once a page is in swap it will stay there until it is needed. So over = the course of time, swap will tend to grow to some stable size, = especially if you have a lot of rarely used services/libraries running. If you have low uptime and high swap, that probably means something in = your initial startup is using a lot of memory, but if the uptime is = long, swap is probably going to grow. And that is fine. You want you memory to be used. I looks to me like your system is quite well used in terms of memory. = There is 156M of free memory, but plenty of inactive and purgeable = (laundry) which looks like a healthy system to me. These are the important numbers, as long as the Free number is low, then = high numbers in inac/laundry are what you want. If these are low and = Free is also low, then your system is struggling. --=20 I don't talk about problems, I disintegrate them.
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