[lug] Swap Space Used Despite Plenty of Memory

[Riggs, Rob]

Linux, and most Unixes, use the RAM to cache frequently used data and
applications. Some of that data is more frequently used than even some of
the programs that are running (actually in state "sleep") on your system. It
makes sense for the OS to swap out the sleeping programs to free up space to
cache your data.

For instance, I run mingettys on VT1-6. That's six application instances
that haven't been used since I last booted this box 17 days ago. No need to
keep those apps in RAM when I have better uses for it. They are all swapped
out at the moment.

A better utility than "top" for insight into memory usage is the program
"free".

$ free
             total       used       free     shared    buffers     cached
Mem:        906340     432624     473716      54772     272160      97304
-/+ buffers/cache:      63160     843180
Swap:       265032       6380     258652

That tells me that in reality I have 63M used and 843M free. The rest of the
432M used is devoted to cached data.

-Rob


-----Original Message-----
From: Dhruva B. Reddy [mailto:sledgehammer2010 at yahoo.com]
Sent: Monday, January 07, 2002 12:37 PM
To: Boulder Linux Users Group
Subject: [lug] Swap Space Used Despite Plenty of Memory


I have always wondered why 'top' shows that my system is using a little
bit of swap space, despite having plenty of physical memory (some of
which is still free, as can be seen below).  Here are the stats:

 12:29:32 up 2 days, 18:48,  7 users,  load average: 0.09, 0.04, 0.01
 109 processes: 108 sleeping, 1 running, 0 zombie, 0 stopped
 CPU states:   0.2% user,   2.0% system,   0.0% nice,  97.8% idle
 Mem:   1030304K total,  1019328K used,    10976K free,    35112K
 buffers
 Swap:  1526132K total,     4752K used,  1521380K free,   727976K cached

Any insights?

Thanks,
Dhruva

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