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From:   "Luck, Tony" <tony.luck@intel.com>
To:     Steven Rostedt <rostedt@goodmis.org>
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Subject: RE: [PATCH v4 09/10] trace: platform/x86/intel/ifs: Add trace point
 to track Intel IFS operations
Thread-Topic: [PATCH v4 09/10] trace: platform/x86/intel/ifs: Add trace point
 to track Intel IFS operations
Thread-Index: AQHYVoPmGcq84+Hs50ec7Nq4KoK2Oa0BMJaA//+oPOA=
Date:   Mon, 25 Apr 2022 16:49:35 +0000
Message-ID: <1752057af33e4eb28bcea0fd75e44048@intel.com>
References: <20220419163859.2228874-1-tony.luck@intel.com>
        <20220422200219.2843823-1-tony.luck@intel.com>
        <20220422200219.2843823-10-tony.luck@intel.com>
 <20220425105251.3f5e8021@gandalf.local.home>
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> > Add tracing support which may be useful for debugging systems that fail=
 to complete
> > In Field Scan tests.
> >
> > Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> > Signed-off-by: Tony Luck <tony.luck@intel.com>
> > ---
> >  MAINTAINERS                              |  1 +
> >  drivers/platform/x86/intel/ifs/runtest.c |  5 ++++
> >  include/trace/events/intel_ifs.h         | 38 ++++++++++++++++++++++++
>
> From the tracing POV:
>
> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Question for the future of this driver.  There are a couple more scan tools=
 coming
in the future. The interface is similar:

	WRMSR to start a scan
	RDMSR to get the results

For this first one, I made the trace code do some user friendly decoding of=
 the
WRMSR value to just show the two interesting fields (start & stop).

The future scan modes will have different fields.

I see two paths:

1) Create a new user friendly trace point for each new scan mode.
2) Just provide a generic one that dumps both the 64-bit WRMSR and RDMSR va=
lues.

Q: Are trace points "expensive" in some way ... so better to just have one =
than three?
     Or are the cheap enough that decoding for the user is an OK thing?

Thanks

-Tony