how to forbid a process to use swap?

[Mehmet Erol Sanliturk]

On Sat, Mar 9, 2013 at 4:30 PM, Anton Shterenlikht <mexas at bristol.ac.uk>wrote:

>         From m.e.sanliturk at gmail.com Sun Mar 10 00:25:27 2013
>
>         On Sat, Mar 9, 2013 at 3:55 PM, Anton Shterenlikht <
> mexas at bristol.ac.uk>wrote:
>
>         > I run a program that uses large arrays.
>         > I don't want it to use swap, because it's
>         > too slow. I want the program to fail when
>         > there's not enough RAM, rather than using
>         > swap. How to do this?
>         >
>         > Is it something to do with these kernel
>         > variables:
>         >
>         > kern.dfldsiz: 34359738368
>         > kern.dflssiz: 8388608
>         >
>         > kern.maxdsiz: 34359738368
>         > kern.maxssiz: 536870912
>         > kern.maxtsiz: 134217728
>         >
>         > Many thanks
>         >
>         > Anton
>         >
>
>
>
>         If you have program source , you may do the following :
>
>
>
>         Define a constant :  Maximum_Allocatable_Memory = ?
>
>
>         Define a variable : Total_Allocated_Memory = 0
>
>
>
>         Before allocating a memory of size M ,
>         check whether  Total_Allocated_Memory + M <
> Maximum_Allocatable_Memory
>
>         If yes : Allocate memory ;
>                   Add M to Total_Allocated_Memory .
>
>         If no :
>
>         Return an error and gracefully stop your program instead of a
> crash which
>         will loose data .
>
> It's a fortran program. I'm not very stong in C.
> Ideally I'd just use the OS (shell) means,
> but I need to understand better which resourse
> limit controls what.
>
> For example, with sh limits(1), I see:
>
> $ limits
> Resource limits (current):
>   cputime              infinity secs
>   filesize             infinity kB
>   datasize               524168 kB
>   stacksize              524168 kB
>   coredumpsize         infinity kB
>   memoryuse            infinity kB
>   memorylocked               64 kB
>   maxprocesses            12200
>   openfiles              117594
>   sbsize               infinity bytes
>   vmemoryuse           infinity kB
>   pseudo-terminals     infinity
>   swapuse              infinity kB
> $
>
> Which of these are relevant to my case?
>
> Finally, the actual problem is on linux,
> but I hope if I'm able to understand how
> things work on FreeBSD, then I could do
> it on linux too, especially if it's just
> a sh command.
>
> Thanks
>
> Anton
>


It is not necessary to know C for the above steps .

If you have source and if it is compilable by Fortran 90 or later standard
, it may use allocation .
( Please see  ALLOCATABLE , ALLOCATE , DEALLOCATE in a Fortran >= 90 manual
).

I am compiling Fortran 77 programs with respect to 2003 standart by
specifying lines as "fixed"
by G95 which it is available in FreeBSD also ( www.g95.org ) . It may be
necessary to convert
Hollerith format specifiers to apostrophes .

Personally I do not any idea about the above parameters .

You may use "System Monitor" or "top" to see memory usage . If there is no
sufficient memory , you may not start your program , or it starts to swap
you may kill suitable programs , etc. .


Thank you very much .

Mehmet Erol Sanliturk