Messages in this thread | | | Date | Wed, 10 Jun 2015 08:51:39 +0200 | From | Ingo Molnar <> | Subject | Re: perf/ftrace: does PERF_EVENT_IOC_SET_FILTER serve any purpose? |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> On Tue, 9 Jun 2015 15:51:53 -0400 (EDT) > Vince Weaver <vincent.weaver@maine.edu> wrote: > > > On Tue, 9 Jun 2015, David Ahern wrote: > > > > > On 6/9/15 12:30 PM, Vince Weaver wrote: > > > > Hello > > > > > > > > I've been working on documenting the PERF_EVENT_IOC_SET_FILTER ioctl. > > > > > > > > I've been trying for the past 2 days and have been unable to get any > > > > result except EINVAL. > > > > > > > > Does anyone ever use this ioctl? Does anyone know how to use this ioctl? > > > > > > yes and yes it works. > > > > > > perf record -e irq:irq_handler_entry --filter irq==28 \ > > > -e irq:softirq_entry --filter vec==6 -a \ > > > -- sleep 5 > > > > # perf record -e irq:irq_handler_entry --filter irq==28 -e irq:softirq_entry --filter vec==6 -a -- sleep 5 > > invalid or unsupported event: 'irq:irq_handler_entry' > > Run 'perf list' for a list of valid events > > > > perf list doesn't show any tracepoint events, despite having debugfs > > mounted and running as root and /sys/kernel/debug/tracing/events/ being > > populated. > > > > What kernel are you using? You may need to update perf. > > We switched to a tracefs filesystem, but the old perf wont read any events if > it's not located in debugfs. That is, it actually tested which filesystem the > event files were mounted on, and if they didn't match the debugfs mount type, it > ignored them. That was fixed recently.
That fix should probably be backported to stable kernels, to keep old instances working.
Thanks,
Ingo
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