Re: Avoiding OOM on overcommit...?

From: David Whysong (dwhysong@physics.ucsb.edu)
Date: Mon Mar 27 2000 - 06:17:34 EST


On Mon, 27 Mar 2000, Peter T. Breuer wrote:
>"A month of sundays ago David Whysong wrote:"

>> the stack still dynamically grows, you have to make sure that you never
>> use more than the preallocated backing store.
>>
>> Is that right?
>
>Yes. But there is nothing to make sure of. I propose that the process
>cannot start unless it has the backing store for its rlimit available -
>and that that store will be bound to it by the kernel for its and it
>alones future use until death do it part.

You want to reserve up to the hard rlimit? That can be a LOT of memory per
process...

A malloc that touches all pages and returns zero on SIGSEGV is
an elegant solution for the heap.

Pre-allocating swap space up to the stack rlimit works, so long as the
kernel handles the case where the rlimit is increased. But this is a less
elegant solution, because you waste some resources in the common case.

I realize I'm splitting hairs here, and root is allowed to kill the
system... but root can increase his hard rlimit.

Dave

David Whysong dwhysong@physics.ucsb.edu
Astrophysics graduate student University of California, Santa Barbara
My public PGP keys are on my web page - http://www.physics.ucsb.edu/~dwhysong
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