linux-kernel - Re: [PATCH 1/3] rcuperf: Remove unnecessary rcu_perf_writer

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Date:   Sun, 21 Aug 2016 16:00:33 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     SeongJae Park <sj38.park@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] rcuperf: Remove unnecessary rcu_perf_writer_state
 variable

On Sun, Aug 21, 2016 at 04:54:38PM +0900, SeongJae Park wrote:
> rcu_perf_writer_state is being written only while nobody reads it.  This
> commit removes the unnecessary variable and macro constants for it.
> 
> Signed-off-by: SeongJae Park <sj38.park@...il.com>
> ---

I am keeping rcu_perf_writer_state for debugging purposes, but I pulled
in the other two patches for review and testing, thank you!

							Thanx, Paul

>  kernel/rcu/rcuperf.c | 16 ++--------------
>  1 file changed, 2 insertions(+), 14 deletions(-)
> 
> diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
> index d38ab08..6025342 100644
> --- a/kernel/rcu/rcuperf.c
> +++ b/kernel/rcu/rcuperf.c
> @@ -86,13 +86,6 @@ static u64 t_rcu_perf_writer_finished;
>  static unsigned long b_rcu_perf_writer_started;
>  static unsigned long b_rcu_perf_writer_finished;
> 
> -static int rcu_perf_writer_state;
> -#define RTWS_INIT		0
> -#define RTWS_EXP_SYNC		1
> -#define RTWS_SYNC		2
> -#define RTWS_IDLE		2
> -#define RTWS_STOPPING		3
> -
>  #define MAX_MEAS 10000
>  #define MIN_MEAS 100
> 
> @@ -381,14 +374,10 @@ rcu_perf_writer(void *arg)
>  	do {
>  		wdp = &wdpp[i];
>  		*wdp = ktime_get_mono_fast_ns();
> -		if (gp_exp) {
> -			rcu_perf_writer_state = RTWS_EXP_SYNC;
> +		if (gp_exp)
>  			cur_ops->exp_sync();
> -		} else {
> -			rcu_perf_writer_state = RTWS_SYNC;
> +		else
>  			cur_ops->sync();
> -		}
> -		rcu_perf_writer_state = RTWS_IDLE;
>  		t = ktime_get_mono_fast_ns();
>  		*wdp = t - *wdp;
>  		i_max = i;
> @@ -429,7 +418,6 @@ rcu_perf_writer(void *arg)
>  			i++;
>  		rcu_perf_wait_shutdown();
>  	} while (!torture_must_stop());
> -	rcu_perf_writer_state = RTWS_STOPPING;
>  	writer_n_durations[me] = i_max;
>  	torture_kthread_stopping("rcu_perf_writer");
>  	return 0;
> -- 
> 1.9.1
>