linux-kernel - Re: [PATCH] of: introduce event tracepoints for dynamic device

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Message-Id: <641aa8ee-9b54-716a-77a1-076cafb95e3a@linux.vnet.ibm.com>
Date:   Wed, 19 Apr 2017 11:45:07 -0700
From:   Tyrel Datwyler <tyreld@...ux.vnet.ibm.com>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Tyrel Datwyler <tyreld@...ux.vnet.ibm.com>, robh+dt@...nel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, nfont@...ux.vnet.ibm.com,
        mpe@...erman.id.au, mingo@...hat.com
Subject: Re: [PATCH] of: introduce event tracepoints for dynamic device_node
 lifecyle

On 04/18/2017 07:49 PM, Steven Rostedt wrote:
> On Tue, 18 Apr 2017 18:42:32 -0700
> Frank Rowand <frowand.list@...il.com> wrote:
> 
>> And of course the other issue with using tracepoints is the extra space
>> required to hold the tracepoint info.  With the pr_debug() approach, the
>> space usage can be easily removed for a production kernel via a config
>> option.
> 
> Now if you are saying you want to be able to enable debugging without
> the tracing infrastructure I would agree. As the tracing infrastructure
> is large. But I'm working on shrinking it more.

The primary consumers of OF_DYNAMIC seem to be pseries and powernv where
we are generally going to see the trace infrastructure enabled by
default in production.

-Tyrel

> 
>>
>> Tracepoints are wonderful technology, but not always the proper tool to
>> use for debug info.
> 
> But if you are going to have tracing enabled regardless, adding a few
> more tracepoints isn't going to make the difference.
> 
> -- Steve
> 
>>
>>> If Rob wants to convert printk() style data to trace data (and I can't
>>> convince him otherwise) then I will have further comments on this specific
>>> patch.
>>>