linux-kernel - Re: [PATCH v2 12/14] platform/x86/intel/ifs: Add current

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Date:   Sat, 12 Nov 2022 20:28:19 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     "Joseph, Jithu" <jithu.joseph@...el.com>,
        "hdegoede@...hat.com" <hdegoede@...hat.com>,
        "markgross@...nel.org" <markgross@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "Macieira, Thiago" <thiago.macieira@...el.com>,
        "Jimenez Gonzalez, Athenas" <athenas.jimenez.gonzalez@...el.com>,
        "Mehta, Sohil" <sohil.mehta@...el.com>
Subject: Re: [PATCH v2 12/14] platform/x86/intel/ifs: Add current_batch sysfs
 entry

On Sat, Nov 12, 2022 at 06:33:58PM +0000, Luck, Tony wrote:
> We tried the full file name in an earlier version. GregKH was
> unimpressed. But that was when we were trying to overload the meaning
> of the “reload” file.

I'm guessing the background of his lack of "impressiveness" was
something along the lines of:

"Attributes should be ASCII text files, preferably with only one value
per file. It is noted that it may not be efficient to contain only one
value per file, so it is socially acceptable to express an array of
values of the same type."

Question is, is a filename string one value per file or strings don't
count?

Suspend allows it:

# echo "shutdown" > /sys/power/disk
# echo "disk" > /sys/power/state

Btw, do you guys really want to run this in production?

As in, are you really that confident that all those test sequence
executions really do not affect other CPU execution at all?

Because if this is going to be run during downtime, as Thiago says, then
you can just as well use debugfs for this. And then there's no need to
cast any API in stone and so on.

Hmmm.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette