On Thu, Sep 26, 2013 at 01:31:06PM +0200, Stephane Eranian wrote: > Jiri, > > On Wed, Sep 25, 2013 at 2:50 PM, Jiri Olsa <jo...@redhat.com> wrote: > > hi, > > sending *RFC* for toggling events support. > > > > Adding perf interface that allows to create toggle events, which can > > enable or disable another event. Whenever the toggle event is triggered > > (has overflow), it toggles another event state and either starts or > > stops it. > > > > The goal is to be able to create toggling tracepoint events to enable and > > disable HW counters, but the interface is generic enough to be used for > > any kind of event. > > > > It's based on the Frederic's patchset: > > https://lkml.org/lkml/2011/3/14/346 > > > > Most of the changelogs info is on wiki: > > https://perf.wiki.kernel.org/index.php/Jolsa_Features_Togle_Event > > > > In a nutshell: > > The interface is added to the sys_perf_event_open syscall > > and new ioctl was added for completeness, check: > > perf: Add event toggle sys_perf_event_open interface > > perf: Add event toggle ioctl interface > > > > The perf tool interface is pretty rough at the moment. We use > > 'on' and 'off' terms to specify the toggling event, like: > > -e 'cycles,irq_entry/on=cycles/,irq_exit/off=cycles/' > > > > Meaning: > > - irq_entry toggles on (starts) cycles, and irq_exit toggled off > > (stops) cycles. > > - cycles is started as paused > > > > Looking forward to some ideas for better interface in here ;-) > > > > The patchset is available at: > > git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > > perf/core_toggle > > > > thanks for comments, > > Such interface is indeed desirable. I received several requests for > this feature internally and externally. > I think it would need to be generalized for user-level code also, same > user API, different trigger points. > I would assume they would be uprobes instead of tracepoints.
not sure what you mean, this code work with uprobes: https://perf.wiki.kernel.org/index.php/Jolsa_Features_Togle_Event#Example_-_using_u.28ret.29probes > > And I agree with you, the current cmdline interface is not good > enough, how about something more > aligned with the current syntax: > -e cpu/event=0x3c,trigger_on=irq_entry,trigger_off=irq_exit/, > that's basically oposite of what we have now, your example would be: -e cpu/event=0x3c,name=cycles/',irq_entry/on=cycles/',irq_exit/off=cycles/' hm, the thing is that you also want to customize trigger events, for example how would you set a filter for irq_entry/irq_exit if needed? maybe allowing extra refference of triggers -e cpu/event=0x3c,trigger_on=irq_entry,trigger_off=irq_exit/' -e 'irq_exit' --filter ... jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
