On Fri, Dec 6, 2013 at 4:43 PM, Masami Hiramatsu <masami.hiramatsu...@hitachi.com> wrote: > (2013/12/05 14:11), Alexei Starovoitov wrote: >> On Wed, Dec 4, 2013 at 4:05 PM, Masami Hiramatsu >> <masami.hiramatsu...@hitachi.com> wrote: >>> (2013/12/04 10:11), Steven Rostedt wrote: >>>> On Wed, 04 Dec 2013 09:48:44 +0900 >>>> Masami Hiramatsu <masami.hiramatsu...@hitachi.com> wrote: >>>> >>>>> fetch functions and actions. In that case, we can continue >>>>> to use current interface but much faster to trace. >>>>> Also, we can see what filter/arguments/actions are set >>>>> on each event. >>>> >>>> There's also the problem that the current filters work with the results >>>> of what is written to the buffer, not what is passed in by the trace >>>> point, as that isn't even displayed to the user. >>> >>> Agreed, so I've said I doubt this implementation is a good >>> shape to integrate. Ktap style is better, since it just gets >>> parameters from perf buffer entry (using event format). >> >> Are you saying always store all arguments into ring buffer and let >> filter run on it? > > Yes, it is what ftrace does. I doubt your way fits all of the existing > trace-event macros. However, I think just for dynamic events, you can > integrating the argument fetching and filtering. > Does this will affect the user interface of perf-probe argument fetching?
I mean if use bpf backend, do we must need gcc to compile bpf source for perf-probe argument fetching? as we known, current argument fetching is go through kprobe_events/uprobe_events debugfs file, and ktap is based on this behavior. Thanks. Jovi. >> It's slower, but it's cleaner, because of human readable? since ktap >> arg1 matches first >> argument of tracepoint is better than doing ctx->regs.di ? Sure. >> si->arg1 is easy to fix. >> With si->arg1 tweak the bpf will become architecture independent. It >> will run through JIT on x86 and through interpreter everywhere else. >> but for kprobes user have to specify 'var=cpu_register' during probe >> creation… how is it better than doing the same in filter? > > Haven't you used perf-probe yet? It already supports such kind of > translation from kernel local variable name to registers, offsets, > and dereference. :) And kprobe-events can parse such arguments into > method chain. See Documentation/trace/kprobetrace.txt and > tools/perf/Documentation/perf-probe.txt for more detail. > Anyway, I'd like to use the bpf for re-implementing fetch method. :) > > Thank you, > > -- > Masami HIRAMATSU > IT Management Research Dept. Linux Technology Center > Hitachi, Ltd., Yokohama Research Laboratory > E-mail: masami.hiramatsu...@hitachi.com > > -- 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/
