From: tmcconne@sedona.intel.com (Tom McConnell~)
Subject: Re: X-station running out of memory
Originator: tmcconne@sedona
Keywords: X-station, memory
Organization: Intel Corporation
Date: Thu, 1 Oct 1992 13:38:19 GMT


In article <1ae790INNq55@agate.berkeley.edu>, jdb@ocf.berkeley.edu (Justin D. Bukowski) writes:
> We have a 550 running simulations and also serving a couple of X-stations.
> 
> One of our researchers is using AVS (visualization program) running
> on another 550 on our network. This other 550 handles all the rendering
> and sends a pixmap to the X-station.
> 
> The researcher logs in to the AVS machine from the X-station
> and starts working. After some time displaying all sorts of pretty
> pictures, the X-station dies, displaying a cursor that looks like a
> thermometer showing 99% on a scale from 0 to 100. It doesn't take much
> thought to guess that it means something has run out of memory.

  Yup. You ran out of "system memory", DRAM, (as opposed to "video
memory", VRAM) in the Xstation. The VRAM just contains the display pixel
information for the current picture. At 2Mb of VRAM you can display a
1280x1024 image at 256 colors (with a 6091 or 5081 monitor), or a 1600x1200
16 color greyscale image. There is no magic about VRAM, it just defines the
limits of what you can display.

  The DRAM, however, is used by the X server on the Xstation to do all the
system overhead. This includes the X server code, off-screen images and fonts.
If you use a lot of pixmaps, which your application appears to do, you can run
out of space and get the thermometer warning

  I believe the DRAM thermometer actually has several levels, not just 99%.
Unfortunately if the pixmaps are large you jump all the way to the end. At 99%
the Xstation starts killing applications.

  As an example, IBM mentions that InfoExplorer uses backing store and large
pixmaps. IBM recommends that at least 1Mb _additional_ DRAM be added if you
intend to use InfoExplorer on the Xstation 130. I would guess that if you
added 1Mb of DRAM for every complex pixmap, the problem would go away. Remember
that you can always break the Xstation by just adding pixmaps, so be
careful :)

  By the way, I have 40+ Xstations here, all with 2Mb VRAM and 4Mb DRAM, and
the only complaint I get is that you cannot put up several 24-bit JPEG images
at the same time. I have not been able to verify it, but I also suspect that
applications that cycle through images (one after the other, but using the same
process) grow the amount of DRAM they use. But I rarely see this, and only when
cycling through a number of large (1000x1000) 24-bit JPEG images using the same
application.

  One more thing, and then I'll be quiet (no really :). IBM has an application
that can watch the resource usage of the X server on the Xstation. If they are
willing, you might be able to get a copy of it. They call it "Xstation Monitor",
and the executable is called "xmonitor". I have a feeling that it is an
internal tool, but you can always ask.

> Justin Bukowski   jdb@ocf.berkeley.edu   jdb@condor.berkeley.edu


    Cheers,

    Tom McConnell
-- 
 Tom McConnell          |     Internet: tmcconne@sedona.intel.com
 Intel, Corp. C3-91     |     Phone: (602)-554-8229
 5000 W. Chandler Blvd. | The opinions expressed are my own. No one in 
 Chandler, AZ  85226    | their right mind would claim them.