Re: How to write marker info in MMIO trace from kernel

[Larry Finger <Larry.Finger@lwfinger.net>]

On 05/04/2010 01:42 PM, Steven Rostedt wrote:
> On Tue, 2010-05-04 at 13:36 -0500, Larry Finger wrote:
>> Stephen,
>>
>> I hope you are the correct person for this question.
>>
>> I would like to write information into the MMIO trace file similar to
>> what the user space write to /sys/.../trace_marker would accomplish,
>> however, I want to do it in place of printk statements in the driver I'm
>> tracing. Do you have any suggestions on how to do this? I have tools to
>> merge the trace dump with dmesg output, but the latter lags behind and I
>> do not get good correlation.
> 
> You can use "trace_printk()". I think that is what you are looking for.

Thanks for the info. One other question - when I write only mmiotrace to
the current_tracer, the trace_printk() stuff does not end up in the
buffer. I can get it by using the "sysprof" tracer, but that has a lot
of stuff I do not want. Did I miss some configuration? My list of
available tracers is "blk kmemtrace mmiotrace wakeup_rt wakeup function
sysprof sched_switch nop".

Thanks,

Larry