Messages in this thread | | | Date | Mon, 25 May 2009 10:04:20 +0200 | From | Damien Wyart <> | Subject | Re: regression: unregister_netdev() unusably slow |
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Hello,
* Eric Dumazet <dada1@cosmosbay.com> [2009-05-25 07:22]: > Time to include Paul and lkml in the discussion, and find a better > solution than one provided in February.
> > bf51935f3e988e0ed6f34b55593e5912f990750a is first bad commit > > commit bf51935f3e988e0ed6f34b55593e5912f990750a > > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Date: Tue Feb 17 06:01:30 2009 -0800
> > x86, rcu: fix strange load average and ksoftirqd behavior
> > Damien Wyart reported high ksoftirqd CPU usage (20%) on an > > otherwise idle system.
> > The function-graph trace Damien provided: > > ... > > diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
> > index a546f55..bd4da2a 100644 > > --- a/arch/x86/kernel/process_32.c > > +++ b/arch/x86/kernel/process_32.c > > @@ -104,9 +104,6 @@ void cpu_idle(void) > > check_pgt_cache(); > > rmb();
> > - if (rcu_pending(cpu)) > > - rcu_check_callbacks(cpu, 0); > > - > > if (cpu_is_offline(cpu)) > > play_dead();
> I wonder if the real root of the problem was not discovered in the meantime, > by commit 64ca5ab913f1594ef316556e65f5eae63ff50cee > rcu: increment quiescent state counter in ksoftirqd()
> Maybe this commit solved Damien Wyart problem as well, and we can revert > commit bf51935f3e988e0ed6f34b55593e5912f990750a ?
Ran some tests on 2.6.30-rc7 with bf51935f reverted, and I am still seeing the problems I originally reported back in February, so I guess 64ca5ab9 is not enough to fully solve all the issues... Note that I am using CONFIG_TREE_RCU=y (was already true in my February reports).
Feel free to ask if more testing is needed.
-- Damien Wyart
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