Re: [PATCH v2 3/3] trace: Example of "centralized" recorder tracing

[Daniel P . Berrangé]

On Wed, Jul 01, 2020 at 05:09:06PM +0100, Stefan Hajnoczi wrote:
> On Tue, Jun 30, 2020 at 01:41:36PM +0100, Daniel P. Berrangé wrote:
> > On Fri, Jun 26, 2020 at 06:27:06PM +0200, Christophe de Dinechin wrote:
> > IMHO the whole point of having the pluggable trace backend impls, is
> > precisely that we don't have to add multiple different calls in the
> > code. A single trace_qemu_mutex_unlock() is supposed to work with
> > any backend.
> 
> I think an exception is okay when the other trace backends do not offer
> equivalent functionality.
> 
> Who knows if anyone other than Christophe will use this functionality,
> but it doesn't cost much to allow it.

This patch is just an example though, suggesting this kind of usage is
expected to done in other current trace probe locations. The trace wrapper
has most of the information required already including a format string,
so I'd think it could be wired up to the generator so we don't add extra
record() statements through the codebase. At most it should require an
extra annotation in the trace-events file to take the extra parameter
for grouping, and other trace backends can ignore that.

Regards,
Daniel
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