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Message-ID: <20150430104802.239c8943@gandalf.local.home> Date: Thu, 30 Apr 2015 10:48:02 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Jerry Snitselaar <jsnitsel@...hat.com> Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com> Subject: Re: [PATCH] tracing: Export tracing clock functions On Thu, 30 Apr 2015 07:36:40 -0700 Jerry Snitselaar <jsnitsel@...hat.com> wrote: > Critical tracepoint hooks shoud never call anything that takes a lock, > so they are unable to call getrawmonotonic() or ktime_get(). > > Export the rest of the tracing clock functions so can be used in > tracepoint hooks. A little background needs to be explained here. A customer adds their own module to do some analysis and hooks to tracepoints to do so. They were using ktime_get() as their time source, but as that grabs a seq lock, it was causing deadlocks. The tracing clocks were made for this purpose, and I find nothing wrong with letting users add their own modules (GPL of course) and adding their own hooks to the tracepoint code. I created it for that purpose. But if they need to do any timings, they must use lockless clocks, which the trace clocks are good for. -- Steve > > Cc: Steven Rostedt <rostedt@...dmis.org> > Cc: Ingo Molnar <mingo@...hat.com> > Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com> > --- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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