On 14 September 2015 at 09:34, Al Grant Al.Grant@arm.com wrote:
Hi,
the top options for me are:
- restrict to userspace / kernelspace / both
That is taken care of by perf using cmd line options. Tracers are started accordingly but automatically doing the configuration in the tracers can't hurt.
- restrict to one process, or an address range (whatever perf for Intel PT offers here - if it has an option to restrict trace to a specific DSO or the main executable, that would be ideal... would be nice if it worked with ASLR)
Process tracing is perf's signature but we need to add address range. Can you clarify what you mean by DSO and ASLR?
- cycle accurate vs. non cycle accurate: I almost always use cycle-accurate but we must give people the option to disable it in case of overflow or buffer size problems
Ack.
- sync frequency (however good the default is, you might want to change it)
Interesting - I'll have to get back to you on this.
- branch broadcasting / disable return stack - not generally needed, but useful when diagnosing a broken > decode due to JIT etc. (default should be return stack enabled and branch broadcast disabled).
I recall that options. I'll look into it.
I think timestamp and 4-byte CONTEXTIDR should be enabled always... although you could have >experts-only options to disable them.
Having contextID tracing enabled all the time won't be possible when tracing a starting application but should be configurable in other circumstances.
The simpler the better really!
I agree, it has to be simple. I'll run our options by this list once the perf guys get back to me. It's one of those things that requires thinking.
Thanks for taking the time to do this, Mathieu
Al
-----Original Message----- From: Mathieu Poirier [mailto:mathieu.poirier@linaro.org] Sent: 14 September 2015 15:53 To: Al Grant; Mike Leach Cc: coresight@lists.linaro.org Subject: Coresight configuration options
Al and Mike,
With the work on coresight/Perf integration proceeding as planned the time to start looking at how configuration parameters can be conveyed to the tracers using the perf cmd tool is fast approaching, and that's where I need to pick your brain.
In your opinion and based on your experience with coresight, what are the 5 most wanted configuration options we need to start with?
The question could also be thought of as the 5 most common thing people configure when using coresight. Finding a way to give access to all the configuration option of a tracer via cmd line won't be easy but I believe it can be done. If we find a way to address the most commonly used options as an starting point the rest should come easily.
Please think about it and get back to me. My plan is to get the discussion going with the perf maintainer about the best way to proceed sometime this week or the next, depending on schedule.
Thanks, Mathieu
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