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Linux - explain memory usage mem_info output

Could someone clearly explain each LINE of this output from /proc/mem_info

Giving me if a value is GOOD or BAD , REALLY BAD and why it's good or bad.

LINUX REDHAT 7.3 BI PRO Pentium III CPU

        total:    used:    free:  shared: buffers:  cached:
Mem:  524648448 482758656 41889792    49152 20705280 318124032
Swap: 2147442688 297893888 1849548800
MemTotal:       512352 kB
MemFree:         40908 kB
MemShared:          48 kB
Buffers:         20220 kB
Cached:          29900 kB
SwapCached:     280768 kB
Active:         168112 kB
Inact_dirty:    160128 kB
Inact_clean:      2696 kB
Inact_target:   131068 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:       512352 kB
LowFree:         40908 kB
SwapTotal:     2097112 kB
SwapFree:      1806200 kB

Thanks
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eeolivier
Asked:
eeolivier
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1 Solution
 
jlevieCommented:
The only thing notable in that is that there's not enough installed memory to avoid using swap. Whether that's good, bad, or doesn't matter is really a matter of what is swapped out. If something that's actively running is having to use swap there'll be a noticable performance problem with the system. On the other hand if what's in swap is only active at infrequent intervals it may not matter.

Are you asking about this because you've got a problem or just for general knowedge?
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eeolivierAuthor Commented:
In fact, it's in my development server. But i hardly understand what is "Inact_dirty" for example. And High/Low

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owensleftfootCommented:
" The only thing notable in that is that there's not enough installed memory to avoid using swap."

Forgive my ignorance Jim but I thought the kernel would  always use a small amount of swap no matter how much ram is in the box?
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jlevieCommented:
Inact_dirty is memory that's not currently being used but still contains data that needs to be saved to swap or disk. An example would something like file data that hasn't yet been flushed to disk.

HighTotal is the total amount of memory in the high region (above approx 860MB). LowTotal is all other memory below the High region.

That, and more, information about memory stats can be seen at http://www.redhat.com/advice/tips/meminfo.html

owensleftfoot,

There's a difference between swap being occasionally used and data living in swap. I've got servers that you never see any swap usage because they have a ton of memory relative to the load.
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