linux-kernel - Re: [PATCH] rcu: Reword help of RCU

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Date:   Thu, 6 Oct 2016 15:51:34 +0300
From:   Nikolay Borisov <kernel@...p.com>
To:     paulmck@...ux.vnet.ibm.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rcu: Reword help of RCU_TRACE option



On 10/06/2016 03:45 PM, Paul E. McKenney wrote:
> On Wed, Oct 05, 2016 at 05:18:09PM +0300, Nikolay Borisov wrote:
>>
>>
>> On 10/05/2016 05:03 PM, Paul E. McKenney wrote:
>>> On Wed, Oct 05, 2016 at 10:06:21AM +0300, Nikolay Borisov wrote:
>>>> Explicitly state that enabling RCU_TRACE enables more
>>>> tracepoints and not just "additional tracing".
>>>>
>>>> Signed-off-by: Nikolay Borisov <kernel@...p.com>
>>>> ---
>>>>
>>>> Hello Paul, 
>>>>
>>>> Following our latest conversation re. enabling RCU tracing
>>>> I had to actually go and look into the code to see which 
>>>> option enables the additional tracepoints. I wasn't sure
>>>> while reading the help of TRACE_RCU. So here is a patch
>>>> which explicitly states that this enables additional 
>>>> tracepoints. 
>>>>
>>>> Apply it if you deem necessary it might be just me that 
>>>> thinks the description is not verbose enough. 
>>>>
>>>>  lib/Kconfig.debug | 4 ++--
>>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
>>>> index cab7405f48d2..f8c3468ec7ef 100644
>>>> --- a/lib/Kconfig.debug
>>>> +++ b/lib/Kconfig.debug
>>>> @@ -1429,8 +1429,8 @@ config RCU_TRACE
>>>>  	depends on DEBUG_KERNEL
>>>>  	select TRACE_CLOCK
>>>>  	help
>>>> -	  This option provides tracing in RCU which presents stats
>>>> -	  in debugfs for debugging RCU implementation.
>>>> +	  This option enables additional tracepoints in RCU which present
>>>> +	  stats in debugfs for debugging RCU implementation.
>>>
>>> How about something like this?
>>>
>>> 	This option provides tracing in RCU which presents stats
>>> 	in debugfs for debugging RCU implementation.  It also enables
>>> 	additional tracepoints for ftrace-style event tracing.
>>
>> So long as it's explicitly stated that it also enables tracepoints it's
>> all fine by me. Apparently I'm not the only one who got confused. In a
>> question re. CONFIG_RCU_TRACE here is what someone said on IRC:
>>
>> "what's tracepoints do you mean? this option enables the additional
>> statistics permanently."
>>
>> Care to apply it with the revised wording or shall I resend?
> 
> Please see below for the current state.
> 
> 							Thanx, Paul

Splendid, ACK.




> 
> ------------------------------------------------------------------------
> 
> commit a30cd69bdcb1ae12cb243e75eddd608c1798d438
> Author: Nikolay Borisov <kernel@...p.com>
> Date:   Thu Oct 6 05:42:39 2016 -0700
> 
>     rcu: RCU_TRACE enables event tracing as well as debugfs
>     
>     The commit brings the RCU_TRACE Kconfig option's help text up to date
>     by noting that it enables additional event tracing as well as debugfs.
>     
>     Signed-off-by: Nikolay Borisov <kernel@...p.com>
>     [ paulmck:  Do some wordsmithing. ]
>     Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 2b5441812214..7f8e8f3c72ea 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1450,7 +1450,8 @@ config RCU_TRACE
>  	select TRACE_CLOCK
>  	help
>  	  This option provides tracing in RCU which presents stats
> -	  in debugfs for debugging RCU implementation.
> +	  in debugfs for debugging RCU implementation.  It also enables
> +	  additional tracepoints for ftrace-style event tracing.
>  
>  	  Say Y here if you want to enable RCU tracing
>  	  Say N if you are unsure.
>