linux-kernel - Re: [RFC][PATCH 4/3] tracing: Add NMI tracing in hwlat detector

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Message-ID: <20160805121706.2766ea1a@gandalf.local.home>
Date:	Fri, 5 Aug 2016 12:17:06 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Clark Williams <williams@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jon Masters <jcm@...hat.com>, Daniel Wagner <wagi@...om.org>,
	Carsten Emde <C.Emde@...dl.org>
Subject: Re: [RFC][PATCH 4/3] tracing: Add NMI tracing in hwlat detector

On Fri, 5 Aug 2016 17:40:43 +0200
Sebastian Andrzej Siewior <bigeasy@...utronix.de> wrote:


> > Ah, this is when we have GENERIC_SCHED_CLOCK, which would break tracing
> > if any arch that has this also has NMIs. Probably need to look at arm64.  
> 
> arm64 should use the generic code as they don't provide sched_clock()
> (and I doubt they go for the weak jiffy version).

And I'm guessing that arm64 supports NMIs. Is there no NMI safe clock?
I probably need to look at the tracing code. Because you can have the
same issue while tracing in an NMI as well.

-- Steve