linux-kernel - Re: [PATCH] locktorture: make verbose writable and control stats print

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Date:	Fri, 15 Apr 2016 17:19:27 -0700
From:	"Shi, Yang" <yang.shi@...aro.org>
To:	paulmck@...ux.vnet.ibm.com
Cc:	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH] locktorture: make verbose writable and control stats
 print

On 4/15/2016 5:09 PM, Paul E. McKenney wrote:
> On Fri, Apr 15, 2016 at 04:45:32PM -0700, Shi, Yang wrote:
>> On 4/15/2016 4:26 PM, Paul E. McKenney wrote:
>>> On Fri, Apr 15, 2016 at 01:28:11PM -0700, Yang Shi wrote:
>>>> When building locktorture test into kernel image, it keeps printing out
>>>> stats information even though there is no lock type specified.
>>>>
>>>> There is already verbose parameter to control print, but it is read-only,
>>>> so it can't be changed at runtime. Make verbose read-write and control
>>>> stats print.
>>>>
>>>> Signed-off-by: Yang Shi <yang.shi@...aro.org>
>>>
>>> Interesting change!
>>>
>>> But just out of curiosity, when you boot with locktorture built in,
>>> do you specify the shutdown_secs boot parameter?  If so, another
>>
>> No, just use the default value, which is 0 for shutdown_secs.
>>
>>> approach would be to shutdown immediately upon detecting an error
>>> during initialization.
>>
>> In my case, it looks there is not error involved.
>
> You said that there is no lock type specified, but that should mean that
> the default ("spin_lock") is chosen.  If so, I would expect it to just

Yes, spin_lock is chosen by default.

> do the test, at least if locktorture.torture_runnable has been set.

But, the default value of torture_runnable is 0. And, it is readonly 
parameter too. This prevents torture from running if it is built into 
kernel instead of module.

Actually, I'm confused why there is not LOCK_TORTURE_TEST_RUNNABLE 
Kconfig like RCU torture?

Thanks,
Yang

>
> Either way, the usual way to make locktorture shut up would be to boot
> with locktorture.stat_interval=0.
>
>>> If not, I would like to know more about your use case.
>>
>> In my test, I just built locktorture test into kernel instead of a
>> module then check how it behaves, no specific purpose.
>>
>> It sounds like not a normal approach to use it.
>
> Agreed, I do believe that this is a case of "working as designed".
>
> 							Thanx, Paul
>