3gb

I have had some problems getting 3gb to provide more accessable memory. I am unable to get COMMON, either normal or virtual to exceed 2gb. If the .BSS exceeds 2gb the program will not start. Maybe if I was to split the common ? When I tried VC, I could not get a valid setting for the stack size.

Also, can a single array exceed 2gb in ftn95 and /3gb?

Can anyone provide some helpful advice on what I may be doing wrong or how to achieve this.

John

Paul,

Given the lack of response to my questions on extending available memory, could you give me some history of the /3gb option in SLINK.

Has the /3gb switch in SLINK been tested and successfully used?

I have been trying to test it, without sucess, getting either a stack overflow or invalid executable.

When trying to modify the array sizes without the /3gb option, I am also finding the tests are sensitivity to what other programs are runing. I would have expected that as all programs are virtual, then the only variation should be the delay for paging out other programs and not changes to stack overflow errors.

When I tried to test the VC option and not /3gb, common loads from 0x20000000 ( 512mb), limiting the available common size to less than 1,500 mb. Can this be changed ? With the 3gb option, I could not get the program to run, beingh unable to fix stack overflow problems.

My previous question of : can I define multiple arrays in excess of 2gb where each are less than 2gb, still has not been answered. I can not get the linker to generate a valid executable.

I am finding this attempt to increase the available memory, using /3gb to be very frustrating. As a concept, /3gb implies that I should be able to have up to 3gb of addressable memory available to a single process. We have other commercial FE packages which appear to achieve this outcome.

I would be pleased to send you my simple program, which presently consists of initialising and summing the values in 2 arrays.

Regards John

I am short of time right now so I cannot give you a detailed answer to your question immediately. I will try to find time later next week.

Basically the 3gb switch sets a flag in the executable and this makes it aware that the operating system has been limited to a 1GB address space rather than the 2GB which is the default. This limit is imposed on the OS by using the 3GB option in your boot.ini. Only XP and one or two specialised OSs offer this.

After that you get what you get. In my experience you can handle more data but not as much as you might think or like. I have only tested on a single large array and it did appear to make a difference.

We plan to run some tests over the next few weeks. If possible we aim to improve the way in which FTN95 handles memory allocation. We also hope to be able to provide some useful guidelines.

This will take some time - perhaps 4 to 6 weeks.

Paul,

That sound good. I have the recent simple program example for testing memory and have some others I have reported a few years ago, although with an earlier version of the compiler. If it would help, I could find these examples and send them to you.

regards John

Yes please. I will send an email address via your forum email.