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    SubjectRe: [PATCH 8/5] llist: Remove cpu_relax() usage in cmpxchg loops
    On Mon, Sep 12, 2011 at 04:05:58PM +0200, Peter Zijlstra wrote:
    > Subject: llist: Remove cpu_relax() usage in cmpxchg loops
    > From: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > Date: Mon Sep 12 15:50:49 CEST 2011
    >
    > Initial benchmarks show they're a net loss (2 socket wsm):
    >

    May still save power. however:

    > entry = cmpxchg(&head->first, old_entry, new);
    > if (entry == old_entry)
    > break;
    > - cpu_relax();

    You need at least a barrier() then, otherwise the compiler could
    change the memory order in the loop.

    -Andi


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