linux-kernel - Re: [PATCH v2 1/2] time/timekeeping: Fix possible inconsistencies in

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Message-ID: <Z-pKEYr01vEaQDIw@localhost>
Date: Mon, 31 Mar 2025 09:53:53 +0200
From: Miroslav Lichvar <mlichvar@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: John Stultz <jstultz@...gle.com>, LKML <linux-kernel@...r.kernel.org>,
	Stephen Boyd <sboyd@...nel.org>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org,
	kernel-team@...roid.com, Lei Chen <lei.chen@...rtx.com>
Subject: Re: [PATCH v2 1/2] time/timekeeping: Fix possible inconsistencies in
 _COARSE clockids

On Thu, Mar 27, 2025 at 06:32:27PM +0100, Thomas Gleixner wrote:
> On Thu, Mar 27 2025 at 16:42, Miroslav Lichvar wrote:
> > On Thu, Mar 27, 2025 at 10:22:31AM +0100, Thomas Gleixner wrote:
> > To clearly see the difference with the new code, I made an attempt
> > to update the old linux-tktest simulation that was used back when the
> > multiplier adjustment was reworked, but there are too many missing
> > things now and I gave up.
> 
> Can you point me to that code?

It's this thing: https://github.com/mlichvar/linux-tktest

> It would be probably useful to create a test mechanism which allows to
> exercise all of this in a simulated way so we actually don't have to
> wonder every time we change a bit what the consequences are.

Yes, that would be very nice if we could run the timekeeping code in a
deterministic simulated environment with a configurable clocksource,
timing of kernel updates, timing and values of injected adjtimex()
calls, etc. The question is how to isolate it.

-- 
Miroslav Lichvar