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To: jiho@sierra.net
cc: freebsd-questions@freefall.cdrom.com
Subject: Re: 2.0.5 Eager to go into swap 
In-reply-to: Your message of "Thu, 03 Aug 95 19:12:39 -0800."
             <199508040309.AA11016@diamond.sierra.net> 
From: David Greenman <davidg@Root.COM>
Reply-To: davidg@Root.COM
Date: Thu, 03 Aug 1995 21:31:54 -0700
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>You know, I just double checked my ps readouts, and you've certainly 
>got a much better point than my recollection suggested when I read 
>your message.  The "run time set size" values tend to be a LOT larger 
>than the "virtual memory size" values, especially for the X programs 
>(though not for the server itself).
>
>But doesn't each library file from which resources are linked get mapped 
>in its entirety (all text, data and bss) into each linking process's virtual
>memory space?  In that case, how could the "run time set size" be much 
>larger than the "virtual memory size"?  It simply represents how many 
>pages of the virtual memory space are actually in core at the moment. 

   Because mapped files aren't included at all in the VSZ reported by 'ps'.
This is a bug and needs to be fixed. Someday.

>And even though ps reports a "run time set size" that doesn't 
>distinguish shared from private pages (so one would expect overlap 
>between processes), why would it report pages a process hasn't 
>accessed?  In other words, if a process doesn't access an entire 
>library, something less than all of that library's pages should be 
>reflected in that process's "run time set size", even though the size 
>of the entire library is reflected in the process's "virtual memory 
>size".

   Because FreeBSD maps all resident pages into the process at map time to
drastically reduce soft page faults (and thus measurably improve performance).

-DG