Messages in this thread | | | Date | Thu, 20 May 2010 12:07:34 +0200 | From | Frederic Weisbecker <> | Subject | Re: [RFD] Future tracing/instrumentation directions |
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On Thu, May 20, 2010 at 11:31:31AM +0200, Ingo Molnar wrote: > - [ While it's still a long way off, if this trend continues > we eventually might even be able to get rid of the > /debug/tracing/ temporary debug API and get rid of > the ugly in-kernel pretty-printing bits. This is > good: it may make Andrew very happy for a change ;-) > > The main detail here to be careful of is that lots of > people are fond of the simplicity of the > /debug/tracing/ debug UI, so when we replace it we > want to do it by keeping that simple workflow (or > best by making it even simpler). I have a few ideas > how to do this.
How? We can emulate the /debug/tracing result with something like perf trace, still that won't replace the immediate availability of the result of any trace, which makes it valuable for any simplest workflows.
> Regarding performance and complexity, which is our main > worry atm, fortunately there's work going on in that > direction - please see PeterZ's recent string of patches > on lkml: > > 4f41c01: perf/ftrace: Optimize perf/tracepoint interaction for single events > a19d35c: perf: Optimize buffer placement by allocating buffers NUMA aware > ef60777: perf: Optimize the perf_output() path by removing IRQ-disables > fa58815: perf: Optimize the hotpath by converting the perf output buffer to local_t
I would like to highlight the following commit too that _totally_ changes the requirements of our next common ring buffer, whatever it is:
c792061: perf: Disallow mmap() on per-task inherited events
Now we only need to care about local contention, we have removed the support for buffers that contend across cpus in a single process.
Do I understand it right?
> 3) Add the function-tracer and function-graph tracer > as an event and integrate it into perf. > > This will live-test the efficiency of the unification > and brings over the last big ftrace plugin to perf.
I may start to take care of this soon.
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