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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?


    David Whysong
    Astrophysics graduate student University of California, Santa Barbara
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