wired - This is memory that must remain in physical
memory, typically OS memory.
active - memory in physical memory that has been used
inactive - memory in physical memory that hasn't been
used - the sum of the above three (wired + active +
free - memory not used by any process.
What's really important is the pageouts. this is the
number of times that memory is written to the hard
disk to make room for more memory. These swaps are
expensive (time-wise that is) and you want this as low
--- Denis Stanton <email@hidden> wrote:
> Would anyone care to help me understand a bit more
> about what Top tells
> me about memory usage? I'm not sure whether my
> server (eMac 800 MHz
> 1GB) is adequate for the job it is doing. Do I have
> just enough RAM or
> way more than I need? I hoped that TOP would tell
> me, but I'm
> confused. What is the difference between inactive
> and free? or between
> active and used? Why is some memory wired and some
> not? Simple
> electronics suggests that all memory has wires
> somewhere. The
> terminology is not familiar
> Here's part of a snapshot (the top of Top). Could
> someone help me by
> reading out the PhysMem line "in plain English"
> 87.0M wired means you have ........ ?
> 616M active means there is .......... ?
> 308M inactive .........
> 1011M used ........
> 13.2M free ...........
> I'm particularly interested in estimating whether
> this server has
> unused capacity, based on the information below.
> Thank you
> Denis Stanton
> Processes: 69 total, 2 running, 67 sleeping... 310
> Load Avg: 1.85, 1.30, 1.11 CPU usage: 49.5%
> user, 19.8% sys,
> 30.6% idle
> SharedLibs: num = 7, resident = 1.59M code, 136K
> data, 500K LinkEdit
> MemRegions: num = 8135, resident = 773M + 4.42M
> private, 65.0M shared
> PhysMem: 87.0M wired, 616M active, 308M inactive,
> 1011M used, 13.2M
> VM: 4.54G + 3.62M 16950(0) pageins, 93689(0)
> PID COMMAND %CPU TIME #TH #PRTS #MREGS
> RPRVT RSHRD RSIZE
> 4115 top 12.3% 0:32.17 1 14 18
> 268K 248K 564K
> 4081 java 0.0% 0:17.98 26 203 204
> 30.7M 14.0M 40.7M
> 3804 FileMaker 2.6% 2:19:48 5 81 184
> 9.11M 21.5M 20.3M
> 3770 java 0.0% 25:47.75 42 254 275
> 148M 14.0M 139M
> 606 httpd 0.0% 0:32.62 1 8 139
> 216K 3.32M 2.17M
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