Re: Building a tracing userspace tool in the kernel tree

["Chris Friesen" <cfriesen@nortel.com>]

Peter Zijlstra wrote:
> On Thu, 2008-10-09 at 15:16 -0400, Mathieu Desnoyers wrote:
> 
>>Hi Sam,
>>
>>At the kernel summit, people seemed to be interested to have the basic
>>userspace tools required to extract and pretty-print a trace available
>>within the kernel tree. Therefore, what I am trying to do is something
>>along the lines of
>>
>>ltt/usr/
>>ltt/usr/tracectl/    (control tracing)
>>ltt/usr/tracesplice/ (splice buffers to disk)
>>ltt/usr/tracecat/    (merge sort and format the binary buffers into
>>                      human-readable text)
> 
> 
> I'd rather have you provide that interface from the kernel much like
> ftrace does. So we can do:
> 
> # cat /debug/tracing/lttng/trace
> 

Do we really want to reserve memory in the kernel to store all the data? 
  Assuming not, do we really want to have to deal with filesystem 
namespaces in the kernel when interpreting which file we want to log to?

Chris