Re: [patch 00/16] CFS Bandwidth Control v7

Ingo Molnar
2011-07-05T08:51:24Z

* Hu Tao <hutao@cn.fujitsu.com> wrote:

> perf diff output:
>
> # Baseline Delta Shared Object Symbol
> # ........ .......... ................. ...........................
> #
> 0.00% +10.07% [kernel.kallsyms] [k] __lock_acquire
> 0.00% +5.90% [kernel.kallsyms] [k] lock_release
> 0.00% +4.86% [kernel.kallsyms] [k] trace_hardirqs_off_caller
> 0.00% +4.06% [kernel.kallsyms] [k] debug_smp_processor_id
> 0.00% +4.00% [kernel.kallsyms] [k] lock_acquire
> 0.00% +3.81% [kernel.kallsyms] [k] lock_acquired
> 0.00% +3.71% [kernel.kallsyms] [k] lock_is_held
> 0.00% +3.04% [kernel.kallsyms] [k] validate_chain
> 0.00% +2.68% [kernel.kallsyms] [k] check_chain_key
> 0.00% +2.41% [kernel.kallsyms] [k] trace_hardirqs_off
> 0.00% +2.01% [kernel.kallsyms] [k] trace_hardirqs_on_caller

Oh, please measure with lockdep (CONFIG_PROVE_LOCKING) turned off. No
production kernel has it enabled and it has quite some overhead (as
visible in the profile), skewing results.

> 2.04% -0.09% pipe-test-100k [.] main
> 0.00% +1.79% [kernel.kallsyms] [k] add_preempt_count

I'd also suggest to turn off CONFIG_PREEMPT_DEBUG.

Thanks,

Ingo