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I was trying to measure how much memory an application is using in the current moment.

So here we go, free -k -t:

[user@server ~]$ free -k -t
             total       used       free     shared    buffers     cached
Mem:       1026076     581880     444196          0     158656     269704
-/+ buffers/cache:     153520     872556
Swap:            0          0          0
Total:     1026076     581880     444196

Then pmap -x PID wanted to verify:

[user@server ~]$ pmap -x 18503
18503:   /usr/bin/java -jar /home/user/app.jar mycfg.cfg
Address           Kbytes     RSS   Dirty Mode   Mapping
0000000040000000      36      36       0 r-x--  java
0000000040108000       8       8       8 rwx--  java
00000000403d9000       4       0       0 -----    [ anon ]
00000000403da000    1024      12      12 rwx--    [ anon ]
000000004055b000      12       0       0 -----    [ anon ]
000000004055e000    1016      72      72 rwx--    [ anon ]
000000004065c000      12       0       0 -----    [ anon ]
000000004065f000    1016      72      72 rwx--    [ anon ]
00000000407ad000      12       0       0 -----    [ anon ]
00000000407b0000    1016      32      32 rwx--    [ anon ]
00000000408ae000      12       0       0 -----    [ anon ]
00000000408b1000    1016      36      36 rwx--    [ anon ]
00000000409cc000      12       0       0 -----    [ anon ]
00000000409cf000    1016     100     100 rwx--    [ anon ]
0000000040acd000      12       0       0 -----    [ anon ]
0000000040ad0000    1016      72      72 rwx--    [ anon ]
0000000040bce000      12       0       0 -----    [ anon ]
0000000040bd1000    1016      40      40 rwx--    [ anon ]
0000000040ccf000      12       0       0 -----    [ anon ]
0000000040cd2000    1016      36      36 rwx--    [ anon ]
0000000040e8a000      12       0       0 -----    [ anon ]
0000000040e8d000    1016      68      68 rwx--    [ anon ]
0000000040f8b000      12       0       0 -----    [ anon ]
0000000040f8e000    1016      68      68 rwx--    [ anon ]
00000000410dd000      12       0       0 -----    [ anon ]
00000000410e0000    1016      68      68 rwx--    [ anon ]
00000000411de000      12       0       0 -----    [ anon ]
00000000411e1000    1016      36      36 rwx--    [ anon ]
00000000412df000      12       0       0 -----    [ anon ]
00000000412e2000    1016      40      40 rwx--    [ anon ]
000000004144a000      12       0       0 -----    [ anon ]
000000004144d000    1016       8       8 rwx--    [ anon ]
000000004154b000      12       0       0 -----    [ anon ]
000000004154e000    1016      48      48 rwx--    [ anon ]
00000000416a7000      12       0       0 -----    [ anon ]
00000000416aa000    1016      36      36 rwx--    [ anon ]
00000000417a8000      12       0       0 -----    [ anon ]
00000000417ab000    1016      40      40 rwx--    [ anon ]
00000000418ec000      12       0       0 -----    [ anon ]
00000000418ef000    1016      40      40 rwx--    [ anon ]
00000000419ed000      12       0       0 -----    [ anon ]
00000000419f0000    1016      36      36 rwx--    [ anon ]
0000000041aee000      12       0       0 -----    [ anon ]
0000000041af1000    1016      40      40 rwx--    [ anon ]
0000000041c54000      12       0       0 -----    [ anon ]
0000000041c57000    1016      36      36 rwx--    [ anon ]
0000000041d55000      12       0       0 -----    [ anon ]
0000000041d58000    1016       8       8 rwx--    [ anon ]
0000000041e56000       4       0       0 -----    [ anon ]
0000000041e57000    1024       8       8 rwx--    [ anon ]
0000000041f57000      12       0       0 -----    [ anon ]
0000000041f5a000    1016      44      44 rwx--    [ anon ]
0000000042058000      12       0       0 -----    [ anon ]
000000004205b000    1016      68      68 rwx--    [ anon ]
0000000042159000      12       0       0 -----    [ anon ]
000000004215c000    1016      32      32 rwx--    [ anon ]
000000005e532000   10308   10272   10272 rwx--    [ anon ]
00000000eb200000    5312    5312    5312 rwx--    [ anon ]
00000000eb730000   80704       0       0 rwx--    [ anon ]
00000000f0600000   10752    5856    5856 rwx--    [ anon ]
00000000f1080000  161280       0       0 rwx--    [ anon ]
00000000fae00000   21248   11144   11144 rwx--    [ anon ]
00000000fc2c0000   62720       0       0 rwx--    [ anon ]
0000003ac7e00000     112     104       0 r-x--  ld-2.5.so
0000003ac801c000       4       4       4 r-x--  ld-2.5.so
0000003ac801d000       4       4       4 rwx--  ld-2.5.so
0000003ac8200000    1336     540       0 r-x--  libc-2.5.so
0000003ac834e000    2048       0       0 -----  libc-2.5.so
0000003ac854e000      16      16       8 r-x--  libc-2.5.so
0000003ac8552000       4       4       4 rwx--  libc-2.5.so
0000003ac8553000      20      20      20 rwx--    [ anon ]
0000003ac8600000       8       8       0 r-x--  libdl-2.5.so
0000003ac8602000    2048       0       0 -----  libdl-2.5.so
0000003ac8802000       4       4       4 r-x--  libdl-2.5.so
0000003ac8803000       4       4       4 rwx--  libdl-2.5.so
0000003ac8a00000      88      64       0 r-x--  libpthread-2.5.so
0000003ac8a16000    2044       0       0 -----  libpthread-2.5.so
0000003ac8c15000       4       4       4 r-x--  libpthread-2.5.so
0000003ac8c16000       4       4       4 rwx--  libpthread-2.5.so
0000003ac8c17000      16       4       4 rwx--    [ anon ]
0000003ac8e00000     520      20       0 r-x--  libm-2.5.so
0000003ac8e82000    2044       0       0 -----  libm-2.5.so
0000003ac9081000       4       4       4 r-x--  libm-2.5.so
0000003ac9082000       4       4       4 rwx--  libm-2.5.so
0000003ac9e00000      28      20       0 r-x--  librt-2.5.so
0000003ac9e07000    2048       0       0 -----  librt-2.5.so
0000003aca007000       4       4       4 r-x--  librt-2.5.so
0000003aca008000       4       4       4 rwx--  librt-2.5.so
0000003acc600000      84      24       0 r-x--  libnsl-2.5.so
0000003acc615000    2044       0       0 -----  libnsl-2.5.so
0000003acc814000       4       4       4 r-x--  libnsl-2.5.so
0000003acc815000       4       4       4 rwx--  libnsl-2.5.so
0000003acc816000       8       0       0 rwx--    [ anon ]
0000003acce00000      68      52       0 r-x--  libresolv-2.5.so
0000003acce11000    2048       0       0 -----  libresolv-2.5.so
0000003acd011000       4       4       4 r-x--  libresolv-2.5.so
0000003acd012000       4       4       4 rwx--  libresolv-2.5.so
0000003acd013000       8       4       0 rwx--    [ anon ]
00002aaaaaaab000       8       8       0 r-xs-  gcb.jar
00002aaaaaaad000      32      32       0 r-xs-  resources.jar
00002aaaaaaba000      52      52       0 r-x--  libverify.so
00002aaaaaac7000    1020       0       0 -----  libverify.so
00002aaaaabc6000      12      12      12 rwx--  libverify.so
00002aaaaabc9000     164     132       0 r-x--  libjava.so
00002aaaaabf2000    1020       0       0 -----  libjava.so
00002aaaaacf1000      28      20      20 rwx--  libjava.so
00002aaaaacf8000       4       4       0 r-x--    [ anon ]
00002aaaaacf9000       4       4       4 rwx--    [ anon ]
00002aaaaacfa000      32      32      12 rwxs-  18503
00002aaaaad08000      40      24       0 r-x--  libnss_files-2.5.so
00002aaaaad12000    2044       0       0 -----  libnss_files-2.5.so
00002aaaaaf11000       4       4       4 r-x--  libnss_files-2.5.so
00002aaaaaf12000       4       4       4 rwx--  libnss_files-2.5.so
00002aaaaaf13000      56      56       0 r-x--  libzip.so
00002aaaaaf21000    1032       0       0 -----  libzip.so
00002aaaab023000      12      12      12 rwx--  libzip.so
00002aaaab026000    2500    1168    1168 rwx--    [ anon ]
00002aaaab297000   46656       0       0 rwx--    [ anon ]
00002aaaae027000      40      40      40 rwx--    [ anon ]
00002aaaae031000     728       0       0 rwx--    [ anon ]
00002aaaae0e7000      12      12      12 rwx--    [ anon ]
00002aaaae0ea000     156       0       0 rwx--    [ anon ]
00002aaaae111000      24      24      24 rwx--    [ anon ]
00002aaaae117000     312       0       0 rwx--    [ anon ]
00002aaaae165000      44      44      44 rwx--    [ anon ]
00002aaaae170000     120       0       0 rwx--    [ anon ]
00002aaaae18e000      28      16      16 rwx--    [ anon ]
00002aaaae195000     316       0       0 rwx--    [ anon ]
00002aaaae1e4000      44      24      24 rwx--    [ anon ]
00002aaaae1ef000     124       0       0 rwx--    [ anon ]
00002aaaae20e000    1632    1632       0 r-xs-  rt.jar
00002aaaae3a6000     208     208     208 rwx--    [ anon ]
00002aaaae3da000   55144      44       0 r-x--  locale-archive
00002aaab19b4000     160     160       0 r-xs-  bcprov-jdk15-146.jar
00002aaab19dc000      28      28       0 r-xs-  mysql-connector-java-5.1.13-bin.jar
00002aaab19e3000      24      24       0 r-xs-  commons-configuration-1.6.jar
00002aaab19e9000      20      20       0 r-xs-  commons-lang-2.5.jar
00002aaab19ee000       8       8       0 r-xs-  commons-logging-1.1.1.jar
00002aaab19f0000      56      56       0 r-xs-  commons-collections-3.2.1.jar
00002aaab19fe000      12      12       0 r-xs-  jce.jar
00002aaab1a01000      24      24       0 r-xs-  jsse.jar
00002aaab1a07000      12      12       0 r-xs-  sunjce_provider.jar
00002aaab1a0a000      76      72       0 r-x--  libnet.so
00002aaab1a1d000    1028       0       0 -----  libnet.so
00002aaab1b1e000      12      12      12 rwx--  libnet.so
00002aaab1b2f000      16      16       0 r-x--  libnss_dns-2.5.so
00002aaab1b33000    2044       0       0 -----  libnss_dns-2.5.so
00002aaab1d32000       4       4       4 r-x--  libnss_dns-2.5.so
00002aaab1d33000       4       4       4 rwx--  libnss_dns-2.5.so
00002aaab4000000   16432    3272    3272 rwx--    [ anon ]
00002aaab500c000   49104       0       0 -----    [ anon ]
00002b29fc3a7000       8       8       8 rwx--    [ anon ]
00002b29fc3b7000      28      16       0 r-x--  libjli.so
00002b29fc3be000    1028       0       0 -----  libjli.so
00002b29fc4bf000       8       8       8 rwx--  libjli.so
00002b29fc4c1000      12      12      12 rwx--    [ anon ]
00002b29fc4c4000    9320    6500       0 r-x--  libjvm.so
00002b29fcdde000    1032       0       0 -----  libjvm.so
00002b29fcee0000    1748     608     608 rwx--  libjvm.so
00002b29fd095000     232     164     164 rwx--    [ anon ]
00007fff13b03000      84      44      44 rwx--    [ stack ]
00007fff13b34000      16       4       0 r-x--    [ anon ]
ffffffffff600000    8192       0       0 -----    [ anon ]
----------------  ------  ------  ------
total kB          601248   49456   39620

Is the a good way to check it ?

Out of my 1026076 (1GB) memory available is that program really using 600K ?

Have I calculated it right ?

This is a VM server just in case the above matters if u need me to output any other commands let me know, appreciated.

share|improve this question

2 Answers 2

up vote 4 down vote accepted

I assume you're basing your conclusions on this line of your pmap output:

total kB          601248   49456   39620

If so, you're reading it wrong. Those numbers are the total number of kilobytes in use, not bytes, so your JVM has asked for about 600MB of memory, of which 49MB is actually stored in physical memory (the rest is swapped out, or committed but not in use, or whatever). A little of that memory is probably shared with other processes (the mmap'd libraries, for instance) but it's noise in comparison to your process' usage.

share|improve this answer
    
thanks for your answer, I have just this one application using java at all so is it safe to assume that for running a single application java is requiring me to give it 600MB out of my total memory ? does that also means it will be locked or something alike ? What else should I check to make sure of all this ? –  Guapo Aug 21 '11 at 12:27
    
No, that's not a safe assumption. –  womble Aug 21 '11 at 12:39
    
Will those 600MB already in use be locked as in not allowing any other resource to take it if those 600MB are not entirely in use but partially in use as it just requested that much of it but does not actually use it all ? –  Guapo Aug 21 '11 at 21:10

Why dont you use top?

ss: http://www.thegeekstuff.com/wp-content/uploads/2010/01/top-highlight.png usage: http://linux.about.com/od/commands/l/blcmdl1_top.htm

share|improve this answer
    
because that is not what I am looking for :) top will give me roughly the same information I can get out of ps auxf/mmap and that just doesn't tell me what I need to understand. –  Guapo Aug 21 '11 at 12:29
    
true, but its easier to look at data, and you can monitor it in near-realtime... –  quamis Aug 22 '11 at 7:05
    
but doesn't help me with my current issue of finding whether it is all being used by java or not or just allocated but yet can allow other process to bite part of it or not and so on. –  Guapo Aug 22 '11 at 13:11
    
What do you mean by "allow other process to bite part of it"? top shows you the same data as almost any other process info tool you may have. They all display the same 3 columns that really matter. Not sure you understand how they work though. take a look at stackoverflow.com/questions/561245/… for another explanation.. –  quamis Aug 23 '11 at 6:29

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