Messages in this thread | | | Date | Thu, 14 Oct 2010 16:58:13 +0200 | From | Damien Wyart <> | Subject | Re: 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) |
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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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