Memory Mangement Problem in 5.1-RELEASE

Bill Moran wmoran at
Thu Jul 24 13:46:14 PDT 2003

Jeremy Messenger wrote:
> On Thu, 24 Jul 2003 15:53:21 -0400, Bill Moran 
> <wmoran at> wrote:
>> 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.
> Well, the 5.0, old -CURRENT and 4.8 have never touch the swap, until 
> 5.1- CURRENT. My system has 256mb ram and it's always touch swap now. If 
> I compile some stuff, sometime it will get around 300mb swap. Current, I 
> only have Gnome 2.3.x and Opera running, so what my top looks like this:

Well, the old YMMV applies, but I'm not seeing this kind of behaviour.
I'm also not running 5.1-CURRENT, but 5.1-RELEASE, so it may be a newly
introduced problem.  The original poster didn't specify whether he was
using -CURRENT or 5.1-RELEASE.

> Mem: 85M Active, 29M Inact, 51M Wired, 4496K Cache, 35M Buf, 73M Free
> Swap: 512M Total, 79M Used, 433M Free, 15% Inuse

Did something use most of the memory up to start the system swapping?
If it started using swap while there was still 73M free, then that's new
to me.

> But, I will remove the Gnome System Monitor applet, then reboot and see 
> how it goes for the whole afternoon.

I'm not saying that Gnome System Monitor is causing the problem, I'm just
saying that it reports inaccurate numbers.

Bill Moran
Potential Technologies

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