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    SubjectRe: [thisops uV2 02/10] vmstat: Optimize zone counter modifications through the use of this cpu operations
    Some numbers for the cmpxchg implementation (cycles)

    Function Orig Cmpxchg Fallback
    inc_zone_page_state 170 32 196
    __inc_zone_page_s 23 31 26
    inc/dec pairs 347 69 379

    So the fallback is always worse. cmpxchg is only better for the versions
    of zone counters where we need to disable and enable interrupts.

    This would suggest to only use the cmpxchg for arches that have cmpxchg
    local and only in the case of the full versions.

    There are 12 cases of inc_zone_page_state and 13 of dec_zone_page_state
    as well as 7 cases of mod_zone_page_state.

     \ /
      Last update: 2010-11-29 22:01    [W:0.021 / U:31.268 seconds]
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