Messages in this thread | | | Date | Mon, 14 Mar 2011 23:43:46 +0100 | From | Frederic Weisbecker <> | Subject | Re: [RFC PATCH 0/4] perf: Custom contexts |
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On Mon, Mar 14, 2011 at 06:56:03PM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, Mar 14, 2011 at 10:20:53PM +0100, Frederic Weisbecker escreveu: > > On Mon, Mar 14, 2011 at 06:03:15PM -0300, Arnaldo Carvalho de Melo wrote: > > > Em Mon, Mar 14, 2011 at 09:51:02PM +0100, Frederic Weisbecker escreveu: > > > > On Mon, Mar 14, 2011 at 05:43:41PM -0300, Arnaldo Carvalho de Melo wrote: > > > > But starter on a starter? Couldn't grok, could you provide an example? > > > > I have no strong example in mind. > > > > But one may want to count instructions when we are in an interrupt and > > lock A is held. > > Those would be and/or starter/stopper expressions, something like: > > $ perf record -e instructions@(irq:irq_handler_entry(irq=eth0) && lock:lock_acquired(foo_lock))..irq:irq_handler_exit(\1) \ > -e instructions \ > netperf > > when all starters before the stopper are valid, we entered a range.
So, if we want to stop when lock is released, we do:
perf record -e instructions@(irq:irq_handler_entry(irq=eth0) && lock:lock_acquired(foo_lock))..lock:lock_release(foo_lock) && irq:irq_handler_exit(\1) \ -e instructions \ netperf
Or || for stoppers like you do below? Hmm, I'm confused...
> > > Or count instruction when A and B are held. > > Using wildcards that matches just the things we want to make it a bit > more compact: > > $ perf record -e inst*@(irq:*entry(irq=eth0) && lock:*acquired(A) && \ > lock:*acquired(B))..(lock:*release(A) || lock:*release(B)) \ > ./my_workload > > Parenthesis don't have to be used just for filters :) Just like in C, > they can be used to express the list of parameters for a function or for > expressions, etc.
The && make sense. But the || ?
What about:
-e inst*@(lock:*acquire(A)..lock:*release(A))@(lock:*acquire(B)..lock:*release(B))@(irq:*entry(irq=eth0)..irq:*exit(irq=eth0))
That looks to me less confusing.
> > > Or count instruction in page faults happening in read() syscall. > > We would need to use 'perf probe' first to insert the entry and exit > probes on the page fault handling path: > > [root@felicio ~]# perf list *fault* *:*fault* > > List of pre-defined events (to be used in -e): > page-faults OR faults [Software event] > minor-faults [Software event] > major-faults [Software event] > alignment-faults [Software event] > emulation-faults [Software event] > > kvm:kvm_page_fault [Tracepoint event] > [root@felicio ~]# > > But then an expression could be used like I showed above for the > previous use case you mentioned.
Right.
> > > Event range define a state, and anytime you need to profile/trace a > > desired stacked state, starters on starters can be a good solution, > > thus even a common practice. > > See above, is that what you're thinking about?
I'm not sure. I can find the meaning of && in your expressions. But not the meaning of ||. I lack some sleep though :)
But still, I'm all for trying to make a better and smarter way to express these events, following your suggestions, but I'm not sure I have the motivation to write a full parser capable of evaluating near C expressions.
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