Re: Building a tracing userspace tool in the kernel tree

From: Chris Friesen
Date: Thu Oct 09 2008 - 18:35:42 EST


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
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