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

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Message-ID: <20160416000930.GD3687@linux.vnet.ibm.com>
Date:	Fri, 15 Apr 2016 17:09:30 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	"Shi, Yang" <yang.shi@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH] locktorture: make verbose writable and control stats
 print

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

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