Re: Audio I/O parameters

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On Fri, 2013-08-02 at 13:59 -0400, Alan Stern wrote:
> On Fri, 2 Aug 2013, Steven Rostedt wrote:
> 
> > On Fri, 2013-08-02 at 16:36 +0200, Peter Zijlstra wrote:
> > > On Fri, Aug 02, 2013 at 10:14:39AM -0400, Alan Stern wrote:
> > > > URL Clas-3286    2d.h.    1us : local_clock <-perf_event_update_userpage
> > > > URL Clas-3286    2d.h.    2us : watchdog_overflow_callback <-__perf_event_overflow
> > > > URL Clas-3286    2d.h.    3us : arch_trigger_all_cpu_backtrace_handler <-nmi_handle.isra.0
> > > > URL Clas-3286    2d.h.    3us : perf_ibs_nmi_handler <-nmi_handle.isra.0
> > > > URL Clas-3286    2d.h.    3us : perf_ibs_handle_irq <-perf_ibs_nmi_handler
> > > > URL Clas-3286    2d.h.    4us : perf_ibs_handle_irq <-perf_ibs_nmi_handler
> > > > URL Clas-3286    2d.h.    4us!: rcu_nmi_exit <-do_nmi
> > > 
> > > What's cute is that the trace starts when the NMI handler does
> > > local_irq_save(), _not_ when the NMI starts, which is where the hardware
> > > actually disabled interrupts.
> > 
> > Yeah, the NMI can be messing with the tracer. It's built on top of
> > lockdep, which does not handle NMIs. Perhaps we can add NMI handling to
> > the latency tracer, but that may need a bit of work to do that.
> 
> Do you have any suggestions with regard to the two questions in my 
> previous email?

Do you mean the one Peter replied to? Or another one.

I have to apologize, I'm doing admin work on my Red Hat box, and it's
having network issues at the moment.

-- Steve


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