freebsd stable - Mar 2017 - slow machine, swap in use, but more than 5GB of RAM inactive

Hi,

I wonder about the slow speed of my machine while top shows ample
inactive memory:

last pid: 85287;  load averages:  2.56,  2.44, 1.68 
up 6+10:24:45 10:13:36 191 processes: 5 running, 186 sleeping 
CPU 0: 47.1% user,  0.0% nice, 51.4% system, 0.0% interrupt,  1.6% idle 
CPU 1: 38.4% user,  0.0% nice, 60.4% system,  0.0% interrupt, 1.2% idle 
CPU 2: 38.8% user,  0.0% nice, 59.2% system,  0.0% interrupt, 2.0% idle 
CPU 3: 45.5% user,  0.0% nice, 51.0% system,  0.4% interrupt, 3.1% idle 
Mem: 677M Active, 5600M Inact, 1083M Wired, 178M Cache, 816M Buf,301M
Free 
Swap: 16G Total, 1352M Used, 15G Free, 8% Inuse

The swap space in use can be explained by large compilations done
recently. Why is the inactive memory not put to use.

I do not want to restart the machine. So, if I could help find the
source of the problem, I would do.

Erich

On Tue, Mar 07, 2017 at 10:19:35AM +0800, Erich Dollansky wrote:
> Hi,
> 
> I wonder about the slow speed of my machine while top shows ample
> inactive memory:
> 
> last pid: 85287;  load averages:  2.56,  2.44, 1.68 
> up 6+10:24:45 10:13:36 191 processes: 5 running, 186 sleeping 
> CPU 0: 47.1% user,  0.0% nice, 51.4% system, 0.0% interrupt,  1.6% idle 
> CPU 1: 38.4% user,  0.0% nice, 60.4% system,  0.0% interrupt, 1.2% idle 
> CPU 2: 38.8% user,  0.0% nice, 59.2% system,  0.0% interrupt, 2.0% idle 
> CPU 3: 45.5% user,  0.0% nice, 51.0% system,  0.4% interrupt, 3.1% idle 
> Mem: 677M Active, 5600M Inact, 1083M Wired, 178M Cache, 816M Buf,301M
> Free 
> Swap: 16G Total, 1352M Used, 15G Free, 8% Inuse
> 
> The swap space in use can be explained by large compilations done
> recently. Why is the inactive memory not put to use.
> 
> I do not want to restart the machine. So, if I could help find the
> source of the problem, I would do.
inactive is not 'not used' memory.
this is just pages don't touched in last 10(?) seconds, but all of
this allocated (such as malloc, mmap, sendfile) to application
(userland programs).

On Tue, 7 Mar 2017 10:19:35 +0800, Erich Dollansky wrote:
 > Hi,
 > 
 > I wonder about the slow speed of my machine while top shows ample
 > inactive memory:

( quoting from this top output because it's neater :)

 > last pid: 85287;  load averages:  2.56,  2.44, 1.68 
 > up 6+10:24:45 10:13:36 191 processes: 5 running, 186 sleeping 
 > CPU 0: 47.1% user,  0.0% nice, 51.4% system, 0.0% interrupt,  1.6% idle 
 > CPU 1: 38.4% user,  0.0% nice, 60.4% system,  0.0% interrupt, 1.2% idle 
 > CPU 2: 38.8% user,  0.0% nice, 59.2% system,  0.0% interrupt, 2.0% idle 
 > CPU 3: 45.5% user,  0.0% nice, 51.0% system,  0.4% interrupt, 3.1% idle 
 > Mem: 677M Active, 5600M Inact, 1083M Wired, 178M Cache, 816M Buf,301M
 > Free 
 > Swap: 16G Total, 1352M Used, 15G Free, 8% Inuse

Others have covered the swap / inactive memory issue.

But I'd expect this to be slow, for any new work anyway .. there's next 
to no idle on any CPU.  I'd be asking, what's all of that system usage?

cheers, Ian