(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. > 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/