linux-kernel - Re: [RFC 3/3] tick-sched: Replace jiffie readout with idle

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Message-ID: <20241113214603.GB2331600@google.com>
Date: Wed, 13 Nov 2024 21:46:03 +0000
From: Joel Fernandes <joel@...lfernandes.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [RFC 3/3] tick-sched: Replace jiffie readout with idle_entrytime

On Tue, Nov 12, 2024 at 03:48:43PM +0100, Thomas Gleixner wrote:
> On Sun, Nov 10 2024 at 22:55, Joel Fernandes wrote:
> >
> > +       /*
> > +        * There is some time that passes between when clocksource starts and the
> > +        * first time tick device is setup. Offset basejiff by that.
> > +       */
> > +       basejiff -= DIV_ROUND_DOWN_ULL(tick_first_period, TICK_NSEC);
> 
> We clearly need yet another division here. Especially as that division
> results in the exactly same value every time.

Yeah I fixed it in my v2 but did not post it yet:

https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git/commit/?h=timers/tick-sched&id=60707e27418e3bca026be0bd9b1eacfe2a6ce72a

I will hold back on posting till we finish discussing on this RFC.

thanks,

 - Joel