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    SubjectRe: PATCH(?): linux-2.4.4-pre2: fork should run child first
     "Adam J. Richter" <> writes:


    > It turned out that the particular unix-like system on which
    > these benchmarks were taken had a version of fork that did not run
    > the child first. As it was explained to me then, most of the time,
    > the child process from a fork will do just a few things and then do
    > an exec(), releasing its copy-on-write references to the parent's
    > pages, and that is the big win of copy-on-write for fork() in practice.
    > This oversight was considered a big embarassment for the operating
    > system in question, so I won't name it here.
    > Guess why you're seeing this email. That's right. Linux-2.4.3's
    > fork() does not run the child first.

    Not always, if I understand correctly. Setting to always is putting
    policy in kernel in a small way. If an app wants to fork and exec, it
    should use *vfork* and exec, which is a performance win across many
    OSs because the COW mappings don't even have to be set up, IIRC.


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