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    SubjectRe: [PATCH] SLUB use cmpxchg_local
    On Mon, 27 Aug 2007, Mathieu Desnoyers wrote:

    > * Christoph Lameter ( wrote:
    > > On Mon, 27 Aug 2007, Peter Zijlstra wrote:
    > >
    > > > So, if the fast path can be done with a preempt off, it might be doable
    > > > to suffer the slow path with a per cpu lock like that.
    > >
    > > Sadly the cmpxchg_local requires local per cpu data access. Isnt there
    > > some way to make this less expensive on RT? Acessing cpu local memory is
    > > really good for performance on NUMA since the data is optimally placed and
    > > one can avoid/reduce locking if the process stays tied to the processor.
    > >
    > On the slow path, in slab_new, we already have to reenable interrupts
    > because we can sleep. If we make sure that whenever we return to an irq
    > disable code path we take the current per-cpu data structure again, can
    > we make the preempt-disable/irq-disabled code paths O(1) ?

    Not sure exactly what you are getting at?
    This would mean running __alloc_pages tied to one processor even though
    waiting is possible?

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      Last update: 2007-08-27 22:33    [W:0.019 / U:5.344 seconds]
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