Thanks Steve!

By the way, as you said,  in the multithreaded SE mode, each thread is
allocated a stack space in the physical memory. Will this space be
deallocated and reused when this thread terminates? I found in tru64.hh that
stack_createFunc creates a 8M stack, but I haven't found where the stack is
deallocated. 

Thanks!

Jiayuan

Jiayuan wrote:
> Hey all,
> 
>  
> 
> When I am trying to test the scalability of M5, I ran the splash2 FFT 
> benchmark with 16 cores.  M5 will prints out
> 
>  
> 
> fatal: Out of memory, please increase size of physical memory.
> 
>  
> 
> and then stop the simulation. I don't know how this could happen since 
> obviously FFT is not that data intensive.
> 
> My questions are:
> 
>    1. Do you have any clue about what happened?
>    2. in SE mode, does M5 support page swapping?  If I have a 128M
>       physical memory and I am running 16 threads, each of them allocate
>       more than 8M memory space in the process's VIRTUAL address space,
>       how does M5 handle this situation in SE mode?

You've pretty much answered your own question there... since there's no 
OS in SE mode, there's no paging, so if your program tries to allocate 
more space than the physical memory you've allocated it gives you the 
error message you see above.  Even if the FFT program itself doesn't 
allocate that much, the system does allocate a certain amount of memory 
per thread for stack space (I don't recall how much... it could be 8MB). 
  That's why you may run out as you increase the number of threads even 
without changing the program.

Fortunately it should be easy to fix; as the message says, just increase 
the physical memory size parameter in the configuration file.

Steve

> 
>  
> 
> Thanks!
> 
>  
> 
> Jiayuan
> 
> 
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