Re: [patch 4/4] KVM-trace port to tracepoints

From: Avi Kivity
Date: Wed Jul 23 2008 - 04:08:50 EST

Peter Zijlstra wrote:
On Tue, 2008-07-22 at 21:46 +0300, Avi Kivity wrote:
Jan Kiszka wrote:
That's true - as long as you don't have to add/remove/modify
tracepoints. I had to do this job in the past (not for KVM). Having 1
spot in 1 file (based on generic probes) would be handier in that case
than 5 spots in 3 files. But if the KVM tracepoints are considered
stable in their number and structure, that shouldn't be an issue here.

Tracepoints aren't stable; they are artefacts of the implementation.

Which IMHO makes it unsuitable for trace_mark() as that will be exported
to user-space, and every time you change your tracepoints you'll change
user visible things - not nice.

They are used for debugging (mostly performance related), so changes are expected.

What uses of trace_mark() depend on a stable interface? blktrace?

error compiling committee.c: too many arguments to function

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