Re: [Xen-tools] hi, all. I have a question about xentrace?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> as we all known, xentrace is a lightweight event logging facility present
> in Xen. XenTrace
> can log events at arbitrary control points in the hypervisor.
> my question is that which API or interface does Xen provide to xentrace?
> what is the principle of xentrace? how does the event logged into trace
> buffer?
>
> I had read xentrace.c file; but found no result.

You also need to read xen/common/trace.c and xen/include/xen/trace.h and 
xen/include/public/trace.h

Tracepoints are written into the Xen source code and compiled in.  These use 
the macros in xen/include/xen/trace.h - these cause data to be queued into 
per-CPU buffers that are shared with domain 0.

xentrace.c contains the code for mapping these buffers and reading their 
contents, which are then dumped out to a file.  xentrace_format parses this 
data and prints it out in a readable form.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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