linux-kernel - Re: [PATCH V3 4/4] Sched: Add tracepoint for sched time slice extension

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Message-ID: <20250502123133.4pGihD-W@linutronix.de>
Date: Fri, 2 May 2025 14:31:33 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Prakash Sangappa <prakash.sangappa@...cle.com>,
	linux-kernel@...r.kernel.org, rostedt@...dmis.org,
	mathieu.desnoyers@...icios.com, tglx@...utronix.de,
	kprateek.nayak@....com
Subject: Re: [PATCH V3 4/4] Sched: Add tracepoint for sched time slice
 extension

On 2025-05-02 13:10:44 [+0200], Peter Zijlstra wrote:
> On Fri, May 02, 2025 at 01:02:10PM +0200, Sebastian Andrzej Siewior wrote:
> > On 2025-05-02 11:14:34 [+0200], Peter Zijlstra wrote:
> > > This is horrific coding style. But really why do we need this? I'm not,
> > > in general, a fan of tracepoints.
> > 
> > I suggested a tracepoint so that we see why the NEED_RESCHED flag
> > disappeared. The trace would show a wakeup, the need_resched flag would
> > be set and the flag would disappear without an explanation.
> 
> Would we not see a timer_start event for the hrtick or somesuch?

Yes, we do. That would mean we need timer:hrtimer* in order for the
sched:* to make sense.

Sebastian