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    SubjectRe: High CPU load when machine is idle (related to PROBLEM: Unusually high load average when idle in 2.6.35, 2.6.35.1 and later)
    Hello,

    > With 2.6.36-rc6, I'm seeing a load of around 0.60 when the machine is
    > completely idle. This is similar to what someone reported for the latest
    > 2.6.35.x stables. This is on a core i7 machine, but I've no time to
    > bisect or test earlier versions right now, but I guess this is easy to
    > reproduce on the same plateform.

    After further investigation and cross-checking with the thread "PROBLEM:
    Unusually high load average when idle in 2.6.35, 2.6.35.1 and later",
    I came to the following results:

    - the commit 74f5187ac873042f502227701ed1727e7c5fbfa9 isolated by Tim
    seems to be the culprit;
    - reverting it solves the problem with 2.6.36-rc7 in NOHZ mode: the load
    when idle goes down to 0.00 (which it never does with the patch
    applied)
    - using nohz=no with the commit reverted still gives correct behaviour
    (tested just in case)

    - vanilla 2.6.36-rc7 with this commit applied has the problem (load is
    around 0.60 when machine idle, sometimes less after several hours
    of uptime, but never 0.00), and rebooting with nohz=no makes the
    problem disappear: load goes down to 0.00 quickly after boot process
    has finished.

    I hope this answers the questions raised in the Tim's thread.

    Could someone with knowledge of the commit take a look at the problem?
    It would be a bit annoying to have this problem in 2.6.36, since Tim's
    initial report dates back to 2 weeks ago...

    I can help for further testing if needed.


    Thanks in advance,
    --
    Damien


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