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Old 11-05-2004, 09:47 AM   #1
dhave
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OOo memory use comparison


I have two versions of OpenOffice on my Slackware system. One is version 1.1.3 of the OpenOffice generic installation that I downloaded from the OO.org website. The other is a "KDE integration" version 1.1.1 that I compiled myself. I have a question about memory usage by these two versions of OpenOffice.

These results are from the KDE system guard applet. Each instance of OOo Writer is openied with a blank document.

OOo Writer generic (v. 1.1.3) uses memory as follows:

- Six separate processes, each using 52,300Kb of physical memory and 107,224Kb of virtual memory.

OOo Writer KDE-integration (v. 1.1.1) uses memory as follows:

- Five separate processes, each using 63,180Kb of physical memory and 123,884Kb of virtual memory.

I say "separate processes" because each process, though identical in memory use, is assigned a unique PID.

I'm wondering about total memory footprint, since OOo generic 1.1.3 runs six processes but OOo KDE 1.1.1 runs just five. Each of the OOo generic processes is about 20 percent smaller in terms of memory use, but, if I'm reading the monitor correctly, there are six of them running. If there really are six rather than five processes running, then the total memory use of OOo generic is a lot greater.

I'm wondering if there truly are this many separate processes running. I thought that perhaps there might be some sort of duplication in the report or something.

Can anyone clarify this for me, please?

Last edited by dhave; 11-05-2004 at 10:01 AM.
 
Old 11-05-2004, 12:07 PM   #2
foo_bar_foo
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since the multiple instances are most likely forks of the original
each child gets a copy of the original address space as virtual memory
but this means i think only the page table is coppied !!! at fork
linux uses essentially total virtual memory where each process has access to all memory
so the pointers in the childs page table don't become unique until a write (copy on write)
so once a child process writes to an address that page say 2 or 4m becomes a unique copy..
or takes up ram..
so if one of the child processes is there for instance to handle printing and no printing is done
it uses no memory......
the same can actually be said i think for even the parent process.
time i think time for everyone to think about ram in a new way rather than what's free and what's used.
you processors MMU memory management unit alocates tables out all ram (or even more than all 3Gigs) to every process. plus 1Gig to all kernel processes. MMU for 32 bit processor is 4Gigs wide

someone correct if i'm wrong on some point !

Last edited by foo_bar_foo; 11-05-2004 at 12:09 PM.
 
Old 11-06-2004, 02:28 AM   #3
dhave
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Registered: Oct 2004
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Distribution: Arch, formerly Gentoo and Slackware
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So, tell me if I've got this right: when five OOo processes are reported to be in memory, actually it's just that five different forks have reserved memory if they need it. Until a process actually needs the memory, it's available for use by other processes. But the original process has priority? Or something like that?

Thanks for taking the time to reply to my long post, by the way.
 
  


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