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    SubjectRe: [PATCH] IB/ehca: Serialize HCA-related hCalls on POWER5
     > > +               ehca_lock_hcalls = !(cur_cpu_spec->cpu_user_features
    > > +                                    & PPC_FEATURE_ARCH_2_05);

    > We already talked about this yesterday, but I still feel that checking the
    > instruction set of the CPU should not be used to determine whether a
    > specific device driver implementation is used int hypervisor.

    I had the same reaction... is testing cpu_user_features really the
    best way to detect this issue?

    I'll hold off applying this for a few days so you guys can decide the
    best thing to do. We'll definitely get some fix into 2.6.24 but we
    have time to make a good decision.

    > Regarding the performance problem, have you checked whether converting all
    > your spin_lock_irqsave to spin_lock/spin_lock_irq improves your performance
    > on the older machines? Maybe it's already fast enough that way.

    It does seem that the only places that the hcall_lock is taken also
    use msleep, so they must always be in process context. So you can
    safely just use spin_lock(), right?

    - R.
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      Last update: 2007-12-06 19:45    [W:0.023 / U:9.256 seconds]
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