[ILUG] SUMMARY: determining how much memory is shared between multiple processes?

[Justin Mason]

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Paul Jakma writes:
> On Sun, 3 Oct 2004, Justin Mason wrote:
> 
> > : jm 1313...; top -b -n1 | grep sharetest
> > 23784 jm        16   0 1032 37148  31m 2620    0  0.0  3.6   0:04 sharetest
> > 23788 jm        22   0 1032 37148  31m 2620    0  0.0  3.6   0:02 sharetest
> >
> > : jm 1258...; sudo cat /proc/23784/status
> 
> > VmStk+VmExe+VmLib = 2540, which is pretty close to 2620.
> 
> Hmm, well it seems to use /proc/.../stat and statm, which dont appear 
> to contain quite same values. ah well.
> 
> > hmm. wonder if there's an instrumentation module that'd do it...
> 
> gdb?
> 
> I doubt there's anything that can do it without serious overhead.. 
> (be it runtime or else memory).

oh, BTW, an update on this -- 2.4.19+ vanilla kernels, *not* Red Hat
patched, will successfully report the correct sharing figures in "top" and
"/proc/.../statm".  2.6.x and Red Hat versions won't, though.

- --j.
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