Messages in this thread | | | Date | Tue, 1 Dec 2009 08:12:11 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 1/2] hw-breakpoints: Use struct perf_event_attr to define user breakpoints |
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On Fri, Nov 27, 2009 at 11:33:10PM +0530, K.Prasad wrote: > I suspect this further needs cleanup. Taking a quick look at all the > exported interfaces: > > struct perf_event * > register_user_hw_breakpoint(struct perf_event_attr *attr, > perf_callback_t triggered, > struct task_struct *tsk); > struct perf_event * > modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr, > perf_callback_t triggered, > struct task_struct *tsk); > > void unregister_hw_breakpoint(struct perf_event *bp); > > struct perf_event ** > register_wide_hw_breakpoint(struct perf_event_attr *attr, > perf_callback_t triggered); > > void unregister_wide_hw_breakpoint(struct perf_event **cpu_events); > > It could be further improved to make them more intuitive and > symmetrical, for instance: > > - Merge 'perf_callback_t triggered' with 'struct perf_event_attr' (it is > very much an attribute of the breakpoint) (you may also want to rename > 'triggered' to something else...which is a pending suggestion from the > community - 'triggered' indicates a boolean datatype and not a > callback).
The perf attributes need to be a user and kernel interface (it is a syscall parameter). I don't we should expose what is supposed to be a kernel internal-only address to such user interface, while it's not needed for the user.
But yeah I can rename trigger to "callback" simply.
Note: it's nice to have reviews and suggestions like you do, it makes the things evolving, and I'll happily fix everything you reported (if I agreed with the idea) but feel free to also send patches, it will make it evolve faster :)
> - Make register_<> always return 'struct perf_event *' (just like how > unregister_<> always returns 'void').
That's a bit hard in the case of wide breakpoints as we are maintaining a cpu array of breakpoints.
> - Both unregister_hw_breakpoint() and unregister_wide_hw_breakpoint() > can accept 'struct perf_event *' as parameters.
Same thing here.
> Would you also like to rename register_wide_hw_breakpoint() to > register_kernel_hw_breakpoint() since a) It is used only for > kernel-space requests b) If a per-cpu kernel-space counter is desired in > future, register_wide_hw_breakpoint() name would shrink to > register_hw_breakpoint() causing ambiguity (user or kernel?) and > name-space collision.
Sure, I can rename it, unless you send a patch for that :)
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