*BSD News Article 72857


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From: Ken Bigelow <kbigelow@www.play-hookey.com>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Memory exhaustion w/ XF86
Date: Thu, 04 Jul 1996 18:27:07 +0000
Organization: Erols Internet Services
Lines: 98
Message-ID: <31DC0CFB.41C67EA6@www.play-hookey.com>
References: <4rdilc$etg@winx03.informatik.uni-wuerzburg.de> <31DAD90A.1B92@www.play-hookey.com> <31DC15B1.F93@linpc9.sari.fh-wuerzburg.de>
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job@linpc9.sari.fh-wuerzburg.de wrote:
> 
> Ken Bigelow wrote:
> >
> > Hans-Joachim Both wrote:
> > >
> > > Did enyone of you made the same experience than me with
> > > XFree86 3.1.2 and Netscape 2.x (or 3 beta) under BSD 2.1.0
> > >
> > > When running Netscape I noticed that all bitmaps are cached
> > > in the X server. This is a normal behaviour, of course, but
> > > after a while X takes more than 90 % of the physical core
> > > memory and leeds the system to trashing or even make it
> > > unable to spawn processes.
> > >
> > > Ok, you may say, shut down the server and restart. The difficulty
> > > is that when running xdm a server restart with memory freeing
> > > is not possible as a normal user.
> > >
> > > Has anybody a solution to this problem?
> > >
> >
> > It is true that FreeBSD will use open RAM for caching, but it has always
> > been nice to me about backing off for active applications. Your problem
> > appears to be one of insufficient RAM, at least at first glance.
> > 16 MB
> 
> may be I should be more specific:  the problem is not insufficient main memory.
> during a session with heavy bitmap working, like webbrowsing,
> the bitmaps are cached inside the Xserver, the cache memory is then never being
> released by the server. Observing the memory consumption is very easy with the top command.
> top showes the memory usage of every program and the disk cache useage in percent.
> 
> On the other hand, I started some tests with other image processing tools, like
> xv. xv for example doesnīt store much bitmaps inside the X server at all, just
> 500 k (it rarely goes over 1 mb or so). of course this bitmap memory isnīt
> freed either.
> 
> So, when doing a lot of netscaping, the x server growes in the core larger and larger
> and after a while no more processes can be forked due to exhausted virtual memory.
> 
> (some month ago I was running linux, Xfree 3.1 and netscape on the same machine,
> there have not been these problems of growing X servers at all...)
> 
> Said again, reseting the server is not the solution, since xdm is running and
> restarting the server again and again after logging out automatically.
> But maybe there is a command line option to the x server, which forces him to
> release cache memory (but I do not think so, since I have read the X Docs carefully,
>  did I?).
> 
> So, help is still appreciated,
> 

I have just spent about an hour and a half running Netscape 3.0b4 on X,
using the S3 server provided as part of the 2.1R distribution. I have
both the News reader and the Browser window open, and I am running top
in one of the other xterm windows to observe the effect. I deliberately 
went to sites like http://www.unitedmedia.com which has boogles of
images such as comic strips and political cartoons, just to see if the
S3 server was caching any images. It isn't.

My memory assignments are quite dynamic as expected. In a 20 MB RAM
system, it varies between 12 MB and 14 MB active (13 M as I type this),
with reasonable variations in the other usages. A while back I was
running 236K Cache on the Memory: line, right now it's 175K. Likewise,
the memory allocated to X86_S3 is stable. I suppose if I could spend the
next 24 to 48 hours doing nothing but browsing I might see if something
started growing out of bounds, but it sure doesn't look like it right
now!

I know that Netscape caches all files it reads, first in RAM and then on
disk, but it won't exceed its designated cache size in memory. You might
check on your settings for this in the Options menu, just in case.

Either way, I see no long-term caching assigned to the S3 X server on my
system. If you're using a different server, it might possibly have a bug
in it -- I couldn't say.

In any case, I can't see a correctly-designed Xserver caching more than
the images it is currently holding and displaying. Blanking a window, as
Netscape does when going to another link, should trigger the Xserver to
release the no-longer-used image while its replacement builds.

Before we go any further with this, I'd like a couple of bits of info
you have so far left out: which Xserver are you using and on what video
card? How much system RAM do you have? How big is your swap partition?
And what are all of the entries top reports about Memory: and Swap:
usage?

These numbers may help to pinpoint the source of your problem.

--

Ken

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