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    SubjectRe: (*(unsigned long *)&jiffies)++;
    On Fri, 7 Jan 2000, Petko Manolov wrote:

    >Lock don't hurt anyway.

    Locks definitely _hurt_ performance very badly. Locks don't scale in SMP
    so if you lock the bus all the time only once CPU between the NR_CPUS will
    run and the other will stall at the first memory bus access. Locks also
    prevents the locking-CPU to reorder instructions on IA32. locks hurt also
    in UP for this reason.

    >May be i am not right, but i think there was some simple instructions
    >(not only incl) that force lock before them in both cases.

    You are talking about xchg (and it's 64bit variant) but they are
    unrelated.

    Andrea


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