Re: [PATCH] Support for enabling/disabling tracepoints while a trace experiment is running

[Stan Shebs <stanshebs@earthlink.net>]

On 5/5/11 4:13 PM, Kwok Cheung Yeung wrote:
> On 05/05/2011 19:51, Eli Zaretskii wrote:
>>> Date: Thu, 05 May 2011 18:27:11 +0100
>>> From: Kwok Cheung Yeung<kcy@codesourcery.com>
>>>
>>> +                     If a trace experiment is started with no enabled
>>> +  tracepoints, then a warning will be printed but the experiment will
>>> +  proceed anyway.
>> You mean, if the experiment started with no enabled tracepoints, and
>> the user says "disable", right?  Otherwise, why the warning?
>>
> Originally, it was an error to try to start an experiment with no enabled
> tracepoints because the resulting experiment would never do anything. However,
> with the patch, tracepoints can be re-enabled after the experiment starts, so I
> downgraded the error to a warning. I suppose we could do away with it
> altogether, but then a user who inadvertently disabled all tracepoints might sit
> and wonder why nothing seems to be happening.

Definitely need at least a warning - all too easy to disable everything, 
including all the tracepoints, with a plain "dis", then be well into the 
run before realizing that none of the tracepoints are getting hits recorded.

Of course, that does go against the Unix tradition of putting the 
snakepit in the middle of the living room floor... :-)

"Eh?"

Stan
stan@codesourcery.com