On 09/25/2013 10:07 AM, Masami Hiramatsu wrote: > (2013/09/15 20:28), Hemant wrote: >> Hi Masami, > Hi, and sorry for replying so late. I missed this in my mailbox. > >> On 09/04/2013 01:31 PM, Masami Hiramatsu wrote: >>> (2013/09/04 15:42), Namhyung Kim wrote: >>>> [SNIP] >>>> You need to add it to Documentation/perf-probe.txt too. In addition if >>>> the --sdt option is only able to work with libelf, it should be wrapped >>>> into the #ifdef LIBELF_SUPPORT pair. >>>> >>>> And I'm not sure that it's a good idea to have two behavior on a single >>>> option (S) - show and probe (add). Maybe it can be separated into two >>>> or the S option can be used as a flag with existing --list and --add >>>> option? >>>> >>> Good catch! :) >>> No, that is really bad idea. All probes must be added by "--add" action. >>> So we need a new probe syntax for specifying sdt marker. >>> >>> How about the below syntax? >>> >>> [EVENT=]%PROVIDER:MARKER [ARG ...] >>> >>> Of course, this will require to list up all markers with "%" prefix for >>> continuity. >>> >>> And since --list option is to list up all existing(defined) probe events, >>> I think --markers (as like as --funcs) is better for listing it up. >>> >>> Thank you! >>> >> I have one doubt here. Why do we need [ARG ...] in the syntax you >> specified? I believe these args are to fetched from the sdt notes' >> section of the elf of the executable/library. Or am I taking this in a >> wrong way and this suggested syntax is actually for the uprobe_events >> file in the tracing directory? > Hm, indeed. Since all the arguments of the marker is defined in sdt notes, > we actually don't need to specify each of them. However, other probe syntax > has those arguments. I'd like to keep the same syntax style in the > same command (action) for avoiding confusion.
Hmm, got it. > I recommend this way; at the first step, we just find the marker address from > sdt. And next, we will make the argument available. And eventually, > it is better to introduce "$args" meta argument to fetch all the arguments > of the marker. > > At this point, we can do > > perf probe %foo:bar $args So, at first step (ignoring the arguments), we can go with : perf probe %foo:bar And, once, the argument support is enabled (all the arguments will be fetched at the marker location), we can go with: perf probe %foo:bar $args > > to trace full information from the marker foo:bar. > > Thank you, > -- Thanks Hemant Kumar Shaw -- 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/