[lkml]   [2011]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usage based on semi-formal proof"
    On 05/23/2011 06:18 PM, Paul E. McKenney wrote:

    > OK, so it looks like I need to get this out of the way in order to track
    > down the delays. Or does reverting PeterZ's patch get you a stable
    > system, but with the longish delays in memory_dev_init()? If the latter,
    > it might be more productive to handle the two problems separately.
    > For whatever it is worth, I do see about 5% increase in grace-period
    > duration when switching to kthreads. This is acceptable -- your
    > 30x increase clearly is completely unacceptable and must be fixed.
    > Other than that, the main thing that affects grace period duration is
    > the setting of CONFIG_HZ -- the smaller the HZ value, the longer the
    > grace-period duration.

    for my 1024g system when memory hotadd is enabled in kernel config:
    1. current linus tree + tip tree: memory_dev_init will take about 100s.
    2. current linus tree + tip tree + your tree - Peterz patch:
    a. on fedora 14 gcc: will cost about 4s: like old times
    b. on opensuse 11.3 gcc: will cost about 10s.


    Yinghai Lu

     \ /
      Last update: 2011-05-24 03:29    [W:0.020 / U:1.544 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site