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    SubjectRe: [PATCH 1/4, v2] x86: enlightenment for ticket spin locks - base implementation
    >>> On 30.06.10 at 14:53, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
    > On 06/30/2010 01:52 PM, Jan Beulich wrote:
    >> I fail to see that: Depending on the hypervisor's capabilities, the
    >> two main functions could be much smaller (potentially there wouldn't
    >> even be a need for the unlock hook in some cases),
    >
    > What mechanism are you envisaging in that case?

    A simple yield is better than not doing anything at all.

    >> The list really juts is needed to not pointlessly tickle CPUs that
    >> won't own the just released lock next anyway (or would own
    >> it, but meanwhile went for another one where they also decided
    >> to go into polling mode).
    >
    > Did you measure that it was a particularly common case which was worth
    > optimising for?

    I didn't measure this particular case. But since the main problem
    with ticket locks is when (host) CPUs are overcommitted, it
    certainly is a bad idea to create even more load on the host than
    there already is (the more that these are bursts).

    Jan



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