amd64 process sizes

[Peter Jeremy]

I've been comparing VSZ reported for similar processes on amd64 and
i386 and found that amd64 processes report as vastly larger than I
expected:

i386  amd64
1476   3572  getty
6272  29184  xclock
4784  28020  xdm
6420  30000  xterm
3828   9444  sendmail

I did some further digging into the procfs map for xterm and found
that each of the amd64 shared objects has an additional mapping that
is 255 or 256 pages.  Once you remove those mappings, the sizes are
reasonably similar.  A typical set of mappings is:

0x800f60000 0x800fba000 61 0 0xffffff0027ac2540 r-x 36 18 0x0 COW NC vnode /usr/local/lib/libXaw8.so.8
0x800fba000 0x800fbb000 1 0 0xffffff002765ed20 r-x 1 0 0x2180 COW NC vnode /usr/local/lib/libXaw8.so.8
0x800fbb000 0x8010bb000 18 0 0xffffff0027ac2540 r-x 36 18 0x0 COW NC vnode /usr/local/lib/libXaw8.so.8 [*]
0x8010bb000 0x8010cd000 18 0 0xffffff00274d2c40 rw- 1 0 0x2180 COW NC vnode /usr/local/lib/libXaw8.so.8

0x28284000 0x282d7000 15 0 0xc360ad68 r-x 9 6 0x0 COW NC vnode /usr/local/lib/libXaw8.so.8
0x282d7000 0x282d8000 0 0 0xc3a4b210 r-x 1 0 0x2180 COW NC vnode /usr/local/lib/libXaw8.so.8
0x282d8000 0x282df000 3 0 0xc3aef39c rwx 1 0 0x2180 COW NC vnode /usr/local/lib/libXaw8.so.8

Could someone please explain the purpose of the mapping [*] and what
system resources they occupy.

-- 
Peter Jeremy

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