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    SubjectRe: [PATCH] set_cpus_allowed() for 2.4
    Ingo Molnar wrote:
    > On Mon, 2 Dec 2002, Andrew Morton wrote:
    > > I have observed two problems with the new scheduler, both serious IMO:
    > >
    > > 1) Changed sched_yield() semantics. [...]
    > we noticed this OpenOffice/StarOffice problem in July, while beta-testing
    > RH 8.0. In July Andrea already had another yield implementation in his
    > tree, which was addressing an unrelated yield()-related regression. I'd
    > like to note here that StarOffice/OpenOffice sucked just as much under
    > Andrea's yield() variant as the original (and 2.5) O(1) scheduler variant
    > did.
    > So i talked to Andrea, and we agreed in a rough solution that worked
    > sufficiently well for OpenOffice and the other regression as well. I
    > implemented it and tested it for OpenOffice. You can see (an i suspect
    > later incarnation) of that implementation in Andrea's current tree. My
    > position back then was that we should not try to move the arguably broken
    > 2.4 yield() implementation to 2.5.
    > So this is the history of O(1) yield().
    > fortunately, things have changed since July, since due to NPTL threading
    > the architectural need for user-space yield() has decreased significantly
    > (NPTL uses futexes, no yielding anywhere), so the only worry is behavioral
    > compatibility with LinuxThreads (and other yield() users). I'll forward
    > port the new (well, old) yield() semantics to 2.5 as well, which will be
    > quite similar to the yield() implementation in Andrea's tree.
    > there's another (this time unique) bit implemented by Andrea, a variant of
    > giving newly forked children priority in a more subtle way - i'm testing
    > this change currently, to see whether it has any positive effect on
    > compilation workloads.
    > does this clarify things?

    Yes, thanks. Will we also be seeing the "interactivity estimator" fixes
    in 2.5?
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