Messages in this thread | | | Date | Fri, 27 Apr 2018 08:58:46 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH RFC] tracepoint: Introduce tracepoint callbacks executing with preempt on |
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On Fri, Apr 27, 2018 at 11:40:05AM -0400, Steven Rostedt wrote: > On Fri, 27 Apr 2018 08:38:26 -0700 > "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote: > > > On Fri, Apr 27, 2018 at 10:47:47AM -0400, Steven Rostedt wrote: > > > On Fri, 27 Apr 2018 10:26:29 -0400 (EDT) > > > Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote: > > > > > > > The general approach and the implementation look fine, except for > > > > one small detail: I would be tempted to explicitly disable preemption > > > > around the call to the tracepoint callback for the rcuidle variant, > > > > unless we plan to audit every tracer right away to remove any assumption > > > > that preemption is disabled in the callback implementation. > > > > > > I'm thinking that we do that audit. There shouldn't be many instances > > > of it. I like the idea that a tracepoint callback gets called with > > > preemption enabled. > > > > Are you really sure you want to increase your state space that much? > > Why not? The code I have in callbacks already deals with all sorts of > context - normal, softirq, irq, NMI, preemption disabled, irq > disabled.
But why? Do people really expect good real-time response on systems instrumented with lots of tracing?
Thanx, Paul
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