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Message-ID: <51C98969.40401@intel.com>
Date: Tue, 25 Jun 2013 15:13:29 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Stephane Eranian <eranian@...gle.com>
CC: Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
LKML <linux-kernel@...r.kernel.org>,
David Ahern <dsahern@...il.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
Namhyung Kim <namhyung@...il.com>,
Paul Mackerras <paulus@...ba.org>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 12/15] perf tools: allow non-matching sample types
On 25/06/13 14:23, Stephane Eranian wrote:
> On Mon, Jun 24, 2013 at 3:16 PM, Adrian Hunter <adrian.hunter@...el.com> wrote:
>> Sample types need not be identical to determine
>> the sample id from the event. Only the position
>> of the sample id needs to be the same.
>>
>> Compatible sample types are ones in which the bits
>> defined by PERF_COMPAT_MASK are the same.
>> 'perf_evlist__config()' forces sample types to be
>> compatible on that basis.
>>
> This is indeed a major flaw of the current sampling buffer format.
> I have a patch coming to address this from the kernel side.
>
> I am trying to understand this patch and I am confused by the
> description and especially the structure of COMPAT_MASK.
>
> I agree that if the SAMPLE_ID position remains constant then
> it can be extracted from the body of the sample uniformly.
> The only way to guarantee a fixed position is by ensuring that
> all the sample_types before SAMPLE_ID and either set or
> unset. By before I don't mean in the enum order but in the
> order in which the kernel lays them various sample_types
> in the buffer. And that's determined by perf_output_sample().
> So I don't understand why PERF_SAMPLE_CPU and
> PERF_SAMPLE_STREAM_ID are here.
>
> Any explanation?
There are 2 sample formats: one for sample events and one for other events
(the id sample). In perf tools refer __perf_evsel__parse_sample() vs
perf_evsel__parse_id_sample().
>
>
>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>> ---
>> tools/perf/util/event.h | 6 ++++
>> tools/perf/util/evlist.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++--
>> tools/perf/util/evlist.h | 3 ++
>> tools/perf/util/evsel.c | 41 +++++++++++++++++++++
>> tools/perf/util/evsel.h | 4 +++
>> 5 files changed, 145 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
>> index 1813895..858572f 100644
>> --- a/tools/perf/util/event.h
>> +++ b/tools/perf/util/event.h
>> @@ -65,6 +65,12 @@ struct read_event {
>> PERF_SAMPLE_ID | PERF_SAMPLE_STREAM_ID | \
>> PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD)
>>
>> +#define PERF_COMPAT_MASK \
>> + (PERF_SAMPLE_IP | PERF_SAMPLE_TID | \
>> + PERF_SAMPLE_TIME | PERF_SAMPLE_ADDR | \
>> + PERF_SAMPLE_ID | PERF_SAMPLE_STREAM_ID | \
>> + PERF_SAMPLE_CPU)
>> +
>> struct sample_event {
>> struct perf_event_header header;
>> u64 array[];
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index a660f56..85c4d91 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -49,10 +49,20 @@ struct perf_evlist *perf_evlist__new(void)
>> return evlist;
>> }
>>
>> +static void perf_evlist__set_id_pos(struct perf_evlist *evlist)
>> +{
>> + struct perf_evsel *first = perf_evlist__first(evlist);
>> +
>> + evlist->id_pos = first->id_pos;
>> + evlist->is_pos = first->is_pos;
>> +}
>> +
>> void perf_evlist__config(struct perf_evlist *evlist,
>> struct perf_record_opts *opts)
>> {
>> struct perf_evsel *evsel;
>> + u64 compat = 0;
>> +
>> /*
>> * Set the evsel leader links before we configure attributes,
>> * since some might depend on this info.
>> @@ -68,7 +78,15 @@ void perf_evlist__config(struct perf_evlist *evlist,
>>
>> if (evlist->nr_entries > 1)
>> perf_evsel__set_sample_id(evsel);
>> + compat |= evsel->attr.sample_type & PERF_COMPAT_MASK;
>> }
>> +
>> + list_for_each_entry(evsel, &evlist->entries, node) {
>> + evsel->attr.sample_type |= compat;
>> + perf_evsel__calc_id_pos(evsel);
>> + }
>> +
>> + perf_evlist__set_id_pos(evlist);
>> }
>>
>> static void perf_evlist__purge(struct perf_evlist *evlist)
>> @@ -102,6 +120,7 @@ void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry)
>> {
>> list_add_tail(&entry->node, &evlist->entries);
>> ++evlist->nr_entries;
>> + perf_evlist__set_id_pos(evlist);
>> }
>>
>> void perf_evlist__splice_list_tail(struct perf_evlist *evlist,
>> @@ -110,6 +129,7 @@ void perf_evlist__splice_list_tail(struct perf_evlist *evlist,
>> {
>> list_splice_tail(list, &evlist->entries);
>> evlist->nr_entries += nr_entries;
>> + perf_evlist__set_id_pos(evlist);
>> }
>>
>> void __perf_evlist__set_leader(struct list_head *list)
>> @@ -339,6 +359,55 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
>> return NULL;
>> }
>>
>> +static int perf_evlist__event2id(struct perf_evlist *evlist,
>> + union perf_event *event, u64 *id)
>> +{
>> + const u64 *array = event->sample.array;
>> + ssize_t n;
>> +
>> + n = (event->header.size - sizeof(event->header)) >> 3;
>> +
>> + if (event->header.type == PERF_RECORD_SAMPLE) {
>> + if (evlist->id_pos >= n)
>> + return -1;
>> + *id = array[evlist->id_pos];
>> + } else {
>> + if (evlist->is_pos >= n)
>> + return -1;
>> + n -= evlist->is_pos;
>> + *id = array[n];
>> + }
>> + return 0;
>> +}
>> +
>> +static struct perf_evsel *perf_evlist__event2evsel(struct perf_evlist *evlist,
>> + union perf_event *event)
>> +{
>> + struct hlist_head *head;
>> + struct perf_sample_id *sid;
>> + int hash;
>> + u64 id;
>> +
>> + if (evlist->nr_entries == 1 || evlist->matching_sample_types)
>> + return perf_evlist__first(evlist);
>> +
>> + if (perf_evlist__event2id(evlist, event, &id))
>> + return NULL;
>> +
>> + /* Synthesized events have an id of zero */
>> + if (!id)
>> + return perf_evlist__first(evlist);
>> +
>> + hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
>> + head = &evlist->heads[hash];
>> +
>> + hlist_for_each_entry(sid, head, node) {
>> + if (sid->id == id)
>> + return sid->evsel;
>> + }
>> + return NULL;
>> +}
>> +
>> union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
>> {
>> struct perf_mmap *md = &evlist->mmap[idx];
>> @@ -650,9 +719,26 @@ int perf_evlist__set_filter(struct perf_evlist *evlist, const char *filter)
>> bool perf_evlist__valid_sample_type(struct perf_evlist *evlist)
>> {
>> struct perf_evsel *first = perf_evlist__first(evlist), *pos = first;
>> + bool ok = true;
>>
>> list_for_each_entry_continue(pos, &evlist->entries, node) {
>> - if (first->attr.sample_type != pos->attr.sample_type)
>> + if (first->attr.sample_type != pos->attr.sample_type) {
>> + ok = false;
>> + break;
>> + }
>> + }
>> +
>> + if (ok) {
>> + evlist->matching_sample_types = true;
>> + return true;
>> + }
>> +
>> + if (evlist->id_pos < 0 || evlist->is_pos < 0)
>> + return false;
>> +
>> + list_for_each_entry(pos, &evlist->entries, node) {
>> + if (pos->id_pos != evlist->id_pos ||
>> + pos->is_pos != evlist->is_pos)
>> return false;
>> }
>>
>> @@ -848,7 +934,10 @@ int perf_evlist__start_workload(struct perf_evlist *evlist)
>> int perf_evlist__parse_sample(struct perf_evlist *evlist, union perf_event *event,
>> struct perf_sample *sample)
>> {
>> - struct perf_evsel *evsel = perf_evlist__first(evlist);
>> + struct perf_evsel *evsel = perf_evlist__event2evsel(evlist, event);
>> +
>> + if (!evsel)
>> + return -EFAULT;
>> return perf_evsel__parse_sample(evsel, event, sample);
>> }
>>
>> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
>> index 0583d36..bfcbf67 100644
>> --- a/tools/perf/util/evlist.h
>> +++ b/tools/perf/util/evlist.h
>> @@ -32,11 +32,14 @@ struct perf_evlist {
>> int nr_fds;
>> int nr_mmaps;
>> int mmap_len;
>> + int id_pos;
>> + int is_pos;
>> struct {
>> int cork_fd;
>> pid_t pid;
>> } workload;
>> bool overwrite;
>> + bool matching_sample_types;
>> struct perf_mmap *mmap;
>> struct pollfd *pollfd;
>> struct thread_map *threads;
>> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
>> index d01d2cd..ee0f894 100644
>> --- a/tools/perf/util/evsel.c
>> +++ b/tools/perf/util/evsel.c
>> @@ -46,6 +46,46 @@ static int __perf_evsel__sample_size(u64 sample_type)
>> return size;
>> }
>>
>> +static int __perf_evsel__calc_id_pos(u64 sample_type)
>> +{
>> + u64 mask;
>> + int i, idx;
>> +
>> + if (!(sample_type & PERF_SAMPLE_ID))
>> + return -1;
>> +
>> + mask = sample_type & (PERF_SAMPLE_ID - 1);
>> +
>> + for (i = 0, idx = 0; i < 64; i++) {
>> + if (mask & (1ULL << i))
>> + idx++;
>> + }
>> +
>> + return idx;
>> +}
>> +
>> +static int __perf_evsel__calc_is_pos(u64 sample_type)
>> +{
>> + int idx = 1;
>> +
>> + if (!(sample_type & PERF_SAMPLE_ID))
>> + return -1;
>> +
>> + if (sample_type & PERF_SAMPLE_CPU)
>> + idx += 1;
>> +
>> + if (sample_type & PERF_SAMPLE_STREAM_ID)
>> + idx += 1;
>> +
>> + return idx;
>> +}
>> +
>> +void perf_evsel__calc_id_pos(struct perf_evsel *evsel)
>> +{
>> + evsel->id_pos = __perf_evsel__calc_id_pos(evsel->attr.sample_type);
>> + evsel->is_pos = __perf_evsel__calc_is_pos(evsel->attr.sample_type);
>> +}
>> +
>> void hists__init(struct hists *hists)
>> {
>> memset(hists, 0, sizeof(*hists));
>> @@ -89,6 +129,7 @@ void perf_evsel__init(struct perf_evsel *evsel,
>> INIT_LIST_HEAD(&evsel->node);
>> hists__init(&evsel->hists);
>> evsel->sample_size = __perf_evsel__sample_size(attr->sample_type);
>> + perf_evsel__calc_id_pos(evsel);
>> }
>>
>> struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr, int idx)
>> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
>> index 3f156cc..88b4319 100644
>> --- a/tools/perf/util/evsel.h
>> +++ b/tools/perf/util/evsel.h
>> @@ -71,6 +71,8 @@ struct perf_evsel {
>> } handler;
>> struct cpu_map *cpus;
>> unsigned int sample_size;
>> + int id_pos;
>> + int is_pos;
>> bool supported;
>> bool needs_swap;
>> /* parse modifier helper */
>> @@ -100,6 +102,8 @@ void perf_evsel__delete(struct perf_evsel *evsel);
>> void perf_evsel__config(struct perf_evsel *evsel,
>> struct perf_record_opts *opts);
>>
>> +void perf_evsel__calc_id_pos(struct perf_evsel *evsel);
>> +
>> bool perf_evsel__is_cache_op_valid(u8 type, u8 op);
>>
>> #define PERF_EVSEL__MAX_ALIASES 8
>> --
>> 1.7.11.7
>>
>
>
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