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Date: Mon, 29 Dec 2014 14:58:12 +0200 From: Adrian Hunter <adrian.hunter@...el.com> To: Namhyung Kim <namhyung@...nel.org>, David Ahern <dsahern@...il.com> CC: Arnaldo Carvalho de Melo <acme@...nel.org>, Ingo Molnar <mingo@...nel.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Jiri Olsa <jolsa@...hat.com>, LKML <linux-kernel@...r.kernel.org>, Stephane Eranian <eranian@...gle.com>, Andi Kleen <andi@...stfloor.org>, Frederic Weisbecker <fweisbec@...il.com> Subject: Re: [PATCH 02/37] perf record: Use a software dummy event to track task/mmap events On 27/12/14 07:28, Namhyung Kim wrote: > Hi David, > > On Sat, Dec 27, 2014 at 1:27 AM, David Ahern <dsahern@...il.com> wrote: >> On 12/24/14 12:14 AM, Namhyung Kim wrote: >>> >>> Prepend a software dummy event into evlist to track task/comm/mmap >>> events separately. This is a preparation of multi-file/thread support >>> which will come later. >> >> >> Are you are making this the first event because of how perf internals are >> coded -- that the first event tracks tasks events? With the tracking bit in >> evsel you should not need to do that. Is there another reason? > > Yeah, I know the tracking bit can be set to any evsel in the evlist. > But I'd like to keep it at a fixed index so that it can be easily > identified at later stages (like perf report) too. Ideally, it'd be > great if we have a way to distinguish this auto-added dummy tracking > event from other (user-added) (dummy?) tracking events if any. > >> >> ---8<--- >> >>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c >>> index cfbe2b99b9aa..72dff295237e 100644 >>> --- a/tools/perf/util/evlist.c >>> +++ b/tools/perf/util/evlist.c >>> @@ -193,6 +193,44 @@ int perf_evlist__add_default(struct perf_evlist >>> *evlist) >>> return -ENOMEM; >>> } >>> >>> +int perf_evlist__prepend_dummy(struct perf_evlist *evlist) >>> +{ >>> + struct perf_event_attr attr = { >>> + .type = PERF_TYPE_SOFTWARE, >>> + .config = PERF_COUNT_SW_DUMMY, Probably need .exclude_kernel = 1, here >>> + }; >>> + struct perf_evsel *evsel, *pos; >>> + >>> + event_attr_init(&attr); >>> + >>> + evsel = perf_evsel__new(&attr); >>> + if (evsel == NULL) >>> + goto error; >>> + >>> + /* use strdup() because free(evsel) assumes name is allocated */ >>> + evsel->name = strdup("dummy"); >>> + if (!evsel->name) >>> + goto error_free; >>> + >>> + list_for_each_entry(pos, &evlist->entries, node) { >>> + pos->idx += 1; >>> + pos->tracking = false; >>> + } >>> + >>> + list_add(&evsel->node, &evlist->entries); >>> + evsel->idx = 0; >>> + evsel->tracking = true; >> >> >> perf_evlist__set_tracking_event()? > > I found that after I wrote this, so yes, it can use the function > instead of the oped-code. But the loop traversal is needed anyway to > fixup the evsel->idx. perf_evlist__set_tracking_event() also ensures there is only one tracking event so it is easy to identify. It is the only event with attr->mmap etc set to 1. Then you can use perf_evlist__add(). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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