Re: [PATCH v4 09/10] trace: platform/x86/intel/ifs: Add trace point to track Intel IFS operations

Steven Rostedt
2022-04-26T01:49:37Z

On Mon, 25 Apr 2022 16:49:35 +0000
"Luck, Tony" <tony.luck@intel.com> wrote:

> 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 values.
>
> 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?

Yes, they are expensive as each TRACE_EVENT() can add a few KB of text and
data. But you can add a DECLARE_EVENT_CLASS() and then add "printk"
differences that are less memory heavy.

See DEFINE_EVENT_PRINT().

-- Steve