linux-kernel - Re: Future of NOHZ full/isolation development (was Re: [NOHZ] Remove scheduler_tick_max

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Message-ID: <CAKohpo=U7K==YMytwcGwteTXdf1RFdxo8BoDhfR-9AriL83D8Q@mail.gmail.com>
Date:	Wed, 12 Nov 2014 20:26:05 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Christoph Lameter <cl@...ux.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Gilad Ben-Yossef <gilad@...yossef.com>,
	Tejun Heo <tj@...nel.org>,
	John Stultz <john.stultz@...aro.org>,
	Mike Frysinger <vapier@...too.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Hakan Akkan <hakanakkan@...il.com>,
	Max Krasnyansky <maxk@....qualcomm.com>,
	Hugh Dickins <hughd@...gle.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Kevin Hilman <khilman@...aro.org>
Subject: Re: Future of NOHZ full/isolation development (was Re: [NOHZ] Remove scheduler_tick_max_deferment)

On 12 November 2014 19:24, Frederic Weisbecker <fweisbec@...il.com> wrote:
> I'd rather leave that to tracepoints. Like trace_hrtimer_spurious().

Yeah, it was just to prove things right on the console without getting
into traces.

> Or better yet: have trace_hrtimer_interrupt() which we can compare against
> trace_hrtimer_expire_entry/exit() to check if any hrtimer callback have run
> in the interrupt. This way we avoid workarounds like the above count.

Yeah, I also believe we better add this debug information to mainline kernel.
I will try to get a patch for that soon.

Would it be recommended to add both trace points?
i.e. trace_hrtimer_interrupt() and trace_hrtimer_spurious() ?

--
viresh
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