Messages in this thread | | | Date | Mon, 18 Jul 2011 17:12:33 +0200 | From | Frederic Weisbecker <> | Subject | Re: [RFC 3/4] perf, ftrace: Add new perf ioctl for function trace filter |
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On Mon, Jul 11, 2011 at 03:22:55PM +0200, Jiri Olsa wrote: > As the amount of kernel functions obtained by the ftrace:function tracepoint > is quite big, it's desirable to be able to set the filter on the ftrace > level. > > Added PERF_EVENT_IOC_SET_FTRACE ioctl to be able to specify function filter > for perf event. The interface is the same as for the set_ftrace_filter file. > > Also the same string parser is used as for the set_ftrace_filter file.
I'm not sure I understand why an ioctl is needed for that. Why not using the ftrace filter?
The first idea was to do something like this:
ip == func1 || ip == func2 || ....
But that makes a too long expression. So I thought we could bring support for the "+" operator and have expressions like:
ip == func1 + func2 + func3 + ....
ip == !func1
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