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Date:   Wed, 20 May 2020 22:14:53 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
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        Zhao Yakui <yakui.zhao@intel.com>
Subject: Re: [patch V6 01/37] tracing/hwlat: Use ktime_get_mono_fast_ns()
Message-ID: <20200520201453.GE325280@hirez.programming.kicks-ass.net>
References: <20200515234547.710474468@linutronix.de>
 <20200515235124.466962628@linutronix.de>
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On Sat, May 16, 2020 at 01:45:48AM +0200, Thomas Gleixner wrote:
> Timestamping in the hardware latency detector uses sched_clock() underneath
> and depends on CONFIG_GENERIC_SCHED_CLOCK=n because sched clocks from that
> subsystem are not NMI safe.

AFAICT that's not actually true, see commit:

  1809bfa44e10 ("timers, sched/clock: Avoid deadlock during read from NMI")

that said, no objection to switching to ktime, people that run HPET
clocks deserve all the pain and suffering available with those setups.