Re: [Ltib] Memory Used Ref Design vs Target

[Stuart Hughes]

Hi Tom,

Do you mean the storage size or the run-time RAM requirement?

The storage size can be fairly easily worked out, or seen when ltib
builds the target image.  If you choose other than NFS deployment (that
doesn't trim anything), you'll get a summary of the storage size.  Often
this is compressed.  If you select in the deployment options "Keep
temporary staging directory " rootfs.tmp gets left behind and you can do
'du' and other things to determine the exact uncompressed storage size.

For runtime RAM storage requirements, that's more difficult.  top/free
can help estimate, but as you run things all the memory that is not
being used for running programs will get used for buffer/file caching.
Also I don't think free takes account of the memory needed for the
kernel.  Also, it depends on exactly what you are running, obviously if
you start up more programs, you'll use more RAM.

I have seen people try to estimate this using 'size' and adding up the
various sections.  I've never found this to be overly useful though.

One thing I've done in the past is to artificially reduce the amount of
memory that Linux thinks is available at the command-line by using
'mem=....' and then seeing if all the programs I want to run can still
run.  

I suspect that other lists/forums may also have some ideas.

Regards, Stuart

On Tue, 2007-10-16 at 09:25 -0500, Tom Moulton wrote:
> I am at the point of starting to look at design for my target system.
> 
> I want to make the system as small as possible (but not too small :-) )
> 
> What is the best way to determine the memory required for the system?
> 
> It is simply "top" or "free"
> 
> (Yes assuming I had all possible processes running)
> 
> Is there a more exact way?
> 
> Or maybe better yet, can I tell LTIB only to use 32MB is the RAM?
> (has 128MB on board)
> 
> Thanks
> Tom
> 
> --
> Thomas A. Moulton
> FACTS Engineering
> (727) 375-8888 x114
> 
> 
> 
> 
> 
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