[ltp] help --size of my program too large

[Alexander Gran]

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I'm sure linux can handle more than 1GB for one process, I've got java runn=
ig=20
with up to 1.6GB here, more isn't possible, though(I've got no idea why, bu=
t=20
increasing the maximum heap to more than 1.6GB isn't possible, even on syst=
em=20
with 2GB ram. SGIs Irix has(had? haven't tried recent versions) the same=20
problem, so it may be a java issue). However, I do not see a reason for=20
having such large exceutables, Why don't you just load the data via normal=
=20
IO?

Alex

Am Mittwoch, 2. Juli 2003 00:24 schrieb Tod Harter:
> Ouch!
>
> I'd have to go back and stare at my x86 assembler manuals and whatnot for=
 a
> while to be sure, but I believe you are simply running into a fundamental
> limitation of memory mapping here. That is to say that x86 simply cannot
> map a single segment that is larger than 1G... At least not the way Linux=
's
> memory management is designed. Maybe there are compiler options that let
> Linux load a larger than 1gig ELF into a code segment, but just as a gues=
s,
> probably not...
>
> In my wildest dreams I have never heard of a 1 GIG executeable before! How
> could you have such a huge text segment? I can only suggest a redesign of
> the program so it loads WHATEVER is in that memory AFTER it begins to run,
> in which case it will be in a different segment. Even then I'm highly
> skeptical that Linux on x86 can deal with a single process requiring in
> excess of a gig of address space to be mapped, period.
>
> There are also a host of other potential pitfalls, like I/O to addresses
> over 1 gig requires special workarounds, and it may be that the kernel
> simply can't load across to the 1 gig physical memory barrier.
>
> Even assuming you CAN find the reason for this, I suspect it will be no e=
nd
> of problems. I think you will just have to segment up the problem into
> smaller chunks and process it in stages.
>
> On Tuesday 01 July 2003 02:56 pm, George Jiang wrote:
> > Hi ,  sorry to put this message here. But I know there are a lot of
> > experts on Linux here, and I don't know other pertinent linux
> > newsletters. Thanks.
> >
> > --- Steps ---
> > During my research I have to use a Fortran program for scientific
> > computation.
> > It deals with a large model.
> > first, I use "f77 aa.f -o aa.exe" to compile it;
> > second, I use "size aa.exe" to view the size of the exe file;
> > third, I use "./aa.exe" to run the program.
> >
> > --- Problem ---
> > When the size is larger than 1.0 G, I got the message "Segmentation fau=
lt
> > (cor
> > e dumped)"  when I run "./aa.exe";
> > Then I adjusted the model size, and redo step1,2,3. This time the progr=
am
> > runs
> > well.
> >
> > --- Question ---
> > My computer has 1.5G memory; does anyone know how to fix this problem so
> > that I can run the program with a larger model (my research requires me
> > to run a large model)?  such a
> > s modify the configuration or settings of the Linux system... ( red hat
> > linux 8.0
> > )?
> > ( I've thought about MPI; But it's not easy to modify the program for
> > parralel
> > computing, so I want to find another solution)
> >
> > Thanks a lot!!
> >    George Jiang
> >
> > _________________________________________________________________
> > STOP MORE SPAM with the new MSN 8 and get 2 months FREE*
> > http://join.msn.com/?page=3Dfeatures/junkmail
>
> --
> Tod Harter
> Giant Electronic Brain
> http://www.giantelectronicbrain.com

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