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    SubjectRe: [RFC PATCH 0/4] Gang scheduling in CFS
    On 01/04/2012 06:47 PM, Rik van Riel wrote:
    >> So it looks like the default is optimal, at least wrt the cases you
    >> tested and your test workload.
    > It depends on the workload.
    > I believe ebizzy synchronously bounces messages around between
    > userland threads, and may benefit from lower latency preemption
    > and re-scheduling.
    > Workloads like AMQP do asynchronous messaging, and are likely
    > to benefit from having a lower number of switches.
    > I do not know which kind of workload is more prevalent.
    > Another worry with gang scheduling is scalability. One of
    > the reasons Linux scales well to larger systems is that a
    > lot of things are done CPU local, without communicating
    > things with other CPUs. Making the scheduling algorithm
    > system-global has the potential to add in a lot of overhead.
    > Likewise, removing the ability to migrate workloads to idle
    > CPUs is likely to hurt a lot of real world workloads.
    > Benchmarks don't care, because they run full-out. However,
    > users do not run benchmarks nearly as much as they run
    > actual workloads...

    I think we can solve it at the guest level. The paravirt ticketlock
    stuff introduces wait/wake calls (actually wait is just a HLT
    instruction); we could spin for a while, then HLT until the other side
    wakes us. We should do this for all sites that busy wait.

    error compiling committee.c: too many arguments to function

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      Last update: 2012-01-04 18:19    [W:0.020 / U:25.428 seconds]
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