Memory Mangement Problem in 5.1-RELEASE

Bill Moran wmoran at
Thu Jul 24 12:53:23 PDT 2003

Ahmed Al-Hindawi wrote:
> Hi,
> I have 160Mb of SDRAM (PC100) on a 233Mhz CyrixInstead machine and I
> seem to have memory mangament problems. The BIOS indicates I have 160,
> so does the BSD bootstrap program. 
> When I launch GNOME 2.2 everythings is good as gold untill I open the
> System monitor program. It says that I have 149 Mb of RAM which is fine
> ( 4Mb of video..and the rest...god knows).
> I open every program I have and after 107Mb the machine starts to swap
> with about 50Mb left unused!!
> I recompliled the GENERIC kernal for the sake of it really (Im still an
> amature) I didn't mess with the configuration files or anything (I just
> don't know how!!).
> Is this normal or mismanagement of memory in the 5.1 version of the
> excellent FreeBSD kernel??

The mistake is in the way the Gnome System Monitor display the free memory.

I just watched both 'top' and the System Monitor as I opened program after
program until the system started swapping, and System monitor reports
almost 100M free while top reported less than 10M.

To _always_ have a little memory free is A Good Thing(tm).  FreeBSD has
some pretty advanced memory management that will start swapping _before_
the system runs out of RAM.  However, the System Monitor's display of
this is simply inaccurate.  There was NOT 100M free when it started swapping
on my system.

Bill Moran
Potential Technologies

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