in reply to Re^2: memory usage on x86_64
in thread memory usage on x86_64

And it's still doesn't clear for me, is so much virtual memory requested by perl on 64-bit system is a bug in perl, or correct behaviour.

If you have doubts things are as they should be, you can investigate the virtual memory mappings of the process via /proc/<PID>/maps  (or /proc/self/maps from within the process).  See also proc(5) for a short explanation of the columns.

The following snippet might help with computing sizes: 

#!/usr/bin/perl

open my $maps, "<", "/proc/self/maps" or die $!;

my $sum;
while (<$maps>) {
    /^(\S+)-(\S+)/;
    my $size = hex($2)-hex($1);
    $sum += $size;
    printf "%8d : %s", $size, $_;
}
printf "total: %dk\n", $sum/1024;

[download]

On my current system (64-bit openSUSE 11.1, Perl 5.12.3), it shows 

 1454080 : 00400000-00563000 r-xp 00000000 08:03 1209182              
+              /usr/local/perl/5.12.3/bin/perl
    4096 : 00762000-00763000 r--p 00162000 08:03 1209182              
+              /usr/local/perl/5.12.3/bin/perl
   16384 : 00763000-00767000 rw-p 00163000 08:03 1209182              
+              /usr/local/perl/5.12.3/bin/perl
  270336 : 00767000-007a9000 rw-p 00767000 00:00 0                    
+              [heap]
 1372160 : 7fcc9341c000-7fcc9356b000 r-xp 00000000 08:03 960813       
+              /lib64/libc-2.9.so
 2097152 : 7fcc9356b000-7fcc9376b000 ---p 0014f000 08:03 960813       
+              /lib64/libc-2.9.so
   16384 : 7fcc9376b000-7fcc9376f000 r--p 0014f000 08:03 960813       
+              /lib64/libc-2.9.so
    4096 : 7fcc9376f000-7fcc93770000 rw-p 00153000 08:03 960813       
+              /lib64/libc-2.9.so
   20480 : 7fcc93770000-7fcc93775000 rw-p 7fcc93770000 00:00 0 
   90112 : 7fcc93775000-7fcc9378b000 r-xp 00000000 08:03 960839       
+              /lib64/libpthread-2.9.so
 2097152 : 7fcc9378b000-7fcc9398b000 ---p 00016000 08:03 960839       
+              /lib64/libpthread-2.9.so
    4096 : 7fcc9398b000-7fcc9398c000 r--p 00016000 08:03 960839       
+              /lib64/libpthread-2.9.so
    4096 : 7fcc9398c000-7fcc9398d000 rw-p 00017000 08:03 960839       
+              /lib64/libpthread-2.9.so
   16384 : 7fcc9398d000-7fcc93991000 rw-p 7fcc9398d000 00:00 0 
    8192 : 7fcc93991000-7fcc93993000 r-xp 00000000 08:03 960847       
+              /lib64/libutil-2.9.so
 2093056 : 7fcc93993000-7fcc93b92000 ---p 00002000 08:03 960847       
+              /lib64/libutil-2.9.so
    4096 : 7fcc93b92000-7fcc93b93000 r--p 00001000 08:03 960847       
+              /lib64/libutil-2.9.so
    4096 : 7fcc93b93000-7fcc93b94000 rw-p 00002000 08:03 960847       
+              /lib64/libutil-2.9.so
   53248 : 7fcc93b94000-7fcc93ba1000 r-xp 00000000 08:03 960817       
+              /lib64/libcrypt-2.9.so
 2097152 : 7fcc93ba1000-7fcc93da1000 ---p 0000d000 08:03 960817       
+              /lib64/libcrypt-2.9.so
    4096 : 7fcc93da1000-7fcc93da2000 r--p 0000d000 08:03 960817       
+              /lib64/libcrypt-2.9.so
    4096 : 7fcc93da2000-7fcc93da3000 rw-p 0000e000 08:03 960817       
+              /lib64/libcrypt-2.9.so
  188416 : 7fcc93da3000-7fcc93dd1000 rw-p 7fcc93da3000 00:00 0 
  348160 : 7fcc93dd1000-7fcc93e26000 r-xp 00000000 08:03 960821       
+              /lib64/libm-2.9.so
 2093056 : 7fcc93e26000-7fcc94025000 ---p 00055000 08:03 960821       
+              /lib64/libm-2.9.so
    4096 : 7fcc94025000-7fcc94026000 r--p 00054000 08:03 960821       
+              /lib64/libm-2.9.so
    4096 : 7fcc94026000-7fcc94027000 rw-p 00055000 08:03 960821       
+              /lib64/libm-2.9.so
    8192 : 7fcc94027000-7fcc94029000 r-xp 00000000 08:03 960819       
+              /lib64/libdl-2.9.so
 2097152 : 7fcc94029000-7fcc94229000 ---p 00002000 08:03 960819       
+              /lib64/libdl-2.9.so
    4096 : 7fcc94229000-7fcc9422a000 r--p 00002000 08:03 960819       
+              /lib64/libdl-2.9.so
    4096 : 7fcc9422a000-7fcc9422b000 rw-p 00003000 08:03 960819       
+              /lib64/libdl-2.9.so
   86016 : 7fcc9422b000-7fcc94240000 r-xp 00000000 08:03 960824       
+              /lib64/libnsl-2.9.so
 2093056 : 7fcc94240000-7fcc9443f000 ---p 00015000 08:03 960824       
+              /lib64/libnsl-2.9.so
    4096 : 7fcc9443f000-7fcc94440000 r--p 00014000 08:03 960824       
+              /lib64/libnsl-2.9.so
    4096 : 7fcc94440000-7fcc94441000 rw-p 00015000 08:03 960824       
+              /lib64/libnsl-2.9.so
    8192 : 7fcc94441000-7fcc94443000 rw-p 7fcc94441000 00:00 0 
 1253376 : 7fcc94443000-7fcc94575000 r-xp 00000000 08:03 906609       
+              /usr/lib64/libdb-4.5.so
 2097152 : 7fcc94575000-7fcc94775000 ---p 00132000 08:03 906609       
+              /usr/lib64/libdb-4.5.so
   12288 : 7fcc94775000-7fcc94778000 r--p 00132000 08:03 906609       
+              /usr/lib64/libdb-4.5.so
   12288 : 7fcc94778000-7fcc9477b000 rw-p 00135000 08:03 906609       
+              /usr/lib64/libdb-4.5.so
  122880 : 7fcc9477b000-7fcc94799000 r-xp 00000000 08:03 960806       
+              /lib64/ld-2.9.so
   28672 : 7fcc94922000-7fcc94929000 r--s 00000000 08:03 919953       
+              /usr/lib64/gconv/gconv-modules.cache
  225280 : 7fcc94929000-7fcc94960000 r--p 00000000 08:03 1067394      
+              /usr/lib/locale/de_DE/LC_CTYPE
   16384 : 7fcc94960000-7fcc94964000 rw-p 7fcc94960000 00:00 0 
    8192 : 7fcc94996000-7fcc94998000 rw-p 7fcc94996000 00:00 0 
    4096 : 7fcc94998000-7fcc94999000 r--p 0001d000 08:03 960806       
+              /lib64/ld-2.9.so
    4096 : 7fcc94999000-7fcc9499a000 rw-p 0001e000 08:03 960806       
+              /lib64/ld-2.9.so
   86016 : 7fffb8343000-7fffb8358000 rw-p 7ffffffe9000 00:00 0        
+              [stack]
    4096 : 7fffb83b4000-7fffb83b5000 r-xp 7fffb83b4000 00:00 0        
+              [vdso]
    4096 : ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0    
+              [vsyscall]
total: 22032k

[download]

This should correspond to the VSZ as reported by ps: 

$ /usr/bin/perl -e 'system "ps -p $$ -o rss,vsz,comm"'
  RSS    VSZ COMMAND
 1796  22032 perl

[download]

As you can see, it's mostly mappings to libraries.  But as I already mentioned, a virtual memory mapping doesn't mean it's also using real physical memory...

See also mmap(2).  And maybe Understanding Memory and Understanding The Linux Virtual Memory Manager (PDF, 730p.) for further reading  (I just had those two links within reach — Google's (or DDG's) index knows more fine documents on the subject :)

Replies are listed 'Best First'.
Re^4: memory usage on x86_64
by powerman (Friar) on Feb 16, 2012 at 11:00 UTC
    Thanks. Looks like on 64-bit there is extra line for each library with flags "---p" using each about 2MB, 5 such libraries add about 10MB. So, looks like this issue have nothing with perl itself. Anyway, do you know what these extra lines mean?
[reply]

In Section Seekers of Perl Wisdom