Re: [PATCH] cpuacct: add a branch prediction

[Balbir Singh]

* Li Zefan <lizf@xxxxxxxxxxxxxx> [2009-02-26 15:40:15]:

> cpuacct_charge() is in fast-path, and checking of !cpuacct_susys.active
> always returns false after cpuacct has been initialized at system boot.
> 
> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> ---
>  kernel/sched.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 410eec4..fd2f7fc 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -9589,7 +9589,7 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
>  	struct cpuacct *ca;
>  	int cpu;
> 
> -	if (!cpuacct_subsys.active)
> +	if (unlikely(!cpuacct_subsys.active))

What happens if most distros make cpuacct_subsys active? Can we decide
on unlikely depending on how the system is configured?


-- 
	Balbir
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