Re: tlug: Caldera Japanese version (more comments)

[Jens-Ulrik Petersen <jens-ulrik.petersen@example.com>]

Stephen J. Turnbull <turnbull@example.com> writes:

> >>>>> "juhp" == Jens-Ulrik Petersen <jens-ulrik.petersen@example.com> writes:
> 
>     juhp> basically "memory used" as reported by `free` or `cat
>     juhp> /proc/meminfo` is a high water mark.
> 
> ah, verrrry interrrresting.
> 
> How 'bout that "shared" number?  Presumably libc.so never leaves (on
> Debian even init is dynamically linked!), but suppose you shut down
> all your X11 apps ... do libX11.so.6 et al get flushed from memory?

My guess (to know the exact mechanism there is only one thing to do)
is that libraries and executables that are no longer being used stay
cached in memory until that memory is needed for something else (in
which case they are then dropped from the cache on a memory need
basis) or if the library (or executable) is still in memory and hasn't
been modified on the disk (this part is probably more subtle) its
memory registration is changed back from "cached" to "in use by a
process".  [Hey, this speculating is getting quite fun: I guess it's
finally time to go and read "The Linux Kernel" from the LDP
<http://www.linuxdoc.org/>.]
  
> I assume they would (just keep a reference count), but I can imagine
> that things could get hosed if you're on a development system, and
> dynamic libs might not get flushed in case of say a program crash.

Yep, this might happen if a process zombies but doesn't die?

> That would account for Scott's eventual slows, maybe.

Perhaps.

Jens
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