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SubjectRe: Overcommitable memory??

[CC list trimmed again, I doubt Stephen Tweedie or Rik van Riel are
interested in this discussion.]

On Tue, 21 Mar 2000, James Sutherland wrote:

>>Preventing system OOM using resource limits is equivalent to disabling
>>overcommit. You have to restrict each of N users to 1/N of the total
>>system memory.
>
>No. That is NOT overcommit. Overcommit, in this context, is when a
>process calls malloc() and is given unpopulated address space, which
>will be populated on use.

In the quota case, in order to prevent a system-wide OOM you must give
each of N users an average of 1/N of the total system memory (ignoring
kernel overhead). The side effect is that overcommittment is now
impossible, because the system can only be overcommitted if a user has
exceeded their quota, which is not allowed...

Unless you don't count COW pages against a user's quota?

Dave

David Whysong dwhysong@physics.ucsb.edu
Astrophysics graduate student University of California, Santa Barbara
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