Re: perf/tracepoints access to interpreted strings

David Ahern
2015-04-20T21:27:00Z

On 4/20/15 3:25 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Apr 20, 2015 at 04:46:16PM -0400, Steven Rostedt escreveu:
>> On Wed, 15 Apr 2015 15:09:27 -0300
>> Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>>> If it is strictly an enum, i.e. no holes and just by looking at the
>>> "format" file above I don't see how it could have holes, albeit enums
>>> may have, we can as well have this:
>
>>> const char *perf_evsel__enum(struct perf_evsel *evsel,
>>> struct perf_sample *sample,
>>> const char *enum_name);
>
>>> That would return an array of strings that you could directly access,
>>> indexing using some of the fields.
>
>>> I.e. internally we would see the tracepoint format file as:
>
>>> field:enum action vec; offset:12; size:4; signed:0;
>
>>> enum: action: TIMER, NET_TX, NET_RX, BLOCK, BLOCK_IOPOLL, TASKLET, SCHED, HRTIMER, RCU
>
>> Note, with the new TRACE_DEFINE_ENUM() that was already added to
>> Linus's tree, that print_fmt now looks like:
>
>> print fmt: "vec=%u [action=%s]", REC->vec, __print_symbolic(REC->vec,
>> { 0, "HI" }, { 1, "TIMER" }, { 2, "NET_TX" }, { 3, "NET_RX" }, { 4, "BLOCK" },
>> { 5, "BLOCK_IOPOLL" }, { 6, "TASKLET" }, { 7, "SCHED" }, { 8, "HRTIMER" },
>> { 9, "RCU" })
>
> That is better, indeed, covers holes :-)

Seems to me that means 2 different implementations are needed ... old
and new.