[CentOS] top and allocation issues

On Thu, 03 Mar 2011 15:03:34 -0500, Stephen Harris wrote:


> 
> /proc/sys/vm/overcommit_memory
> (or sysctl vm.overcommit_memory)
> 
>>From the kernel Documentation:
> 
> This value contains a flag that enables memory overcommitment.
> 
> When this flag is 0, the kernel attempts to estimate the amount of free
> memory left when userspace requests more memory.
> 
> When this flag is 1, the kernel pretends there is always enough memory
> until it actually runs out.
> 
> When this flag is 2, the kernel uses a "never overcommit" policy that
> attempts to prevent any overcommit of memory.
> 
> This feature can be very useful because there are a lot of programs that
> malloc() huge amounts of memory "just-in-case" and don't use much of it.
> 
> The default value is 0.
> 

I just wrote a sequence of values (kk % 256) and (after changing
to unsigned char) read back successfully.  I did see some action
in top.

Now given my numbers, it would seem that I am "overcommitted".
Leaving the flag you mention at 0 (which it is), do I run a
risk of a later failure?

Thanks,
Mike.