linux-kernel - Re: [PATCH v5] x86: intel_epb: Add earlyparam option to keep bias at performance

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Message-ID: <20240104090022.41499-1-jalliste@amazon.com>
Date: Thu, 4 Jan 2024 09:00:22 +0000
From: Jack Allister <jalliste@...zon.com>
To: <usama.arif@...edance.com>
CC: <bp@...en8.de>, <corbet@....net>, <dave.hansen@...ux.intel.com>,
	<hdegoede@...hat.com>, <hpa@...or.com>, <jalliste@...zon.com>,
	<juew@...zon.com>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <mingo@...hat.com>, <paulmck@...nel.org>,
	<pdurrant@...zon.com>, <peterz@...radead.org>, <rafael@...nel.org>,
	<rdunlap@...radead.org>, <tglx@...utronix.de>, <tj@...nel.org>,
	<x86@...nel.org>, <yanjiewtw@...il.com>
Subject: Re: [PATCH v5] x86: intel_epb: Add earlyparam option to keep bias at performance

> Thanks for the patch. Is auto needed over here? It was pointed in an 
> earlier review that it could be an option, but it doesn't seem to serve 
> a purpose.

Auto is effectively just the default as if no parameter is passed in here.
In the reply from Dave for he has mentioned that displaying it like this
may actually be clearer.

```
	intel_epb=	[X86]

			auto (default)
```

As we're not implicitly not taking any action for this default case it
doesn't make too much sense to add in a specific strcmp case for auto,
however what I can do is add a comment within the code to explicitly show
that this is effectively a no-op when parsing.

> Maybe add an print in else here to say that unexpected value has been 
> encountered for intel_epb if preserve is not seen.

I'd be hesitant to do this as we already have the pr_warn_once during the
intel_epb_restore path when defaulting from perf -> normal.