Re: New memory exhausted problem

[Dmitri A. Sergatskov]

On 8/13/07, John Swensen <address@hidden> wrote:
> John W. Eaton wrote:

> >
> > You are requesting a single allocation of approximately 1.8GB and you
> > only have about 2GB free.  I'm not sure of the details of the memory
> > management system in the linux kernel, but could it be that it fails
> > because although you have enough total space available, there is no
> > contiguous block of memory available that is large enough?  Maybe
> > someone who knows more about how the allocator is supposed to work
> > could give us a clue here.
> >
> > jwe
> >
> >
> It ends up that that must be the problem.  I figured that it would at
> least go to the swap disk, yet still permit the allocations, but that
> isn't the case.  It was *not* a limitation on the size of an allocation,
> because we tested allocation of a 3.5 GB chunk without any else
> allocated and it seemed to work fine.  So it seems it must be a problem
> with a large allocation when there is little real memory left.
>
> John Swensen

FWIW, it works fine on x86_64 system with only 2GB of physical RAM:


address@hidden ~]$ free
             total       used       free     shared    buffers     cached
Mem:       2062928    2053232       9696          0       2032      40564
-/+ buffers/cache:    2010636      52292
Swap:      6056420    2277316    3779104


address@hidden ~]$ top

....
Mem:   2062928k total,  2052652k used,    10276k free,     2268k buffers
Swap:  6056420k total,  2335444k used,  3720976k free,    56064k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
27836 dima      20   0 3974m 1.7g 1724 S    0 87.5   0:10.43 octave

....


Sincerely,

Dmitri.
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