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Subject[PATCH v16 03/15] perf tools: Update perf evlist mmap related APIs and helpers
Date
Currently, evlist mmap related helpers and APIs accept evlist and idx,
and dereference 'struct perf_mmap' by evlist->mmap[idx]. This is
unnecessary, and force each evlist contains only one mmap array.

Following commits are going to introduce multiple mmap arrays to a evlist.
This patch refators these APIs and helpers, introduces functions accept
perf_mmap pointer directly. New helpers and APIs are decoupled with
perf_evlist, and become perf_mmap functions (so they have perf_mmap prefix).

Old functions are reimplemented with new functions. Some of them will be
removed in following commits.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: pi3orama@163.com
---
tools/perf/util/evlist.c | 139 ++++++++++++++++++++++++++++++++---------------
tools/perf/util/evlist.h | 12 ++++
2 files changed, 108 insertions(+), 43 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 6803f5c..a4137e0 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -29,6 +29,7 @@

static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx);
static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx);
+static void perf_mmap__munmap(struct perf_mmap *map);

#define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
#define SID(e, x, y) xyarray__entry(e->sample_id, x, y)
@@ -781,9 +782,8 @@ broken_event:
return event;
}

-union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int idx)
+union perf_event *perf_mmap__read_forward(struct perf_mmap *md, bool check_messup)
{
- struct perf_mmap *md = &evlist->mmap[idx];
u64 head;
u64 old = md->prev;

@@ -795,13 +795,12 @@ union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int

head = perf_mmap__read_head(md);

- return perf_mmap__read(md, evlist->overwrite, old, head, &md->prev);
+ return perf_mmap__read(md, check_messup, old, head, &md->prev);
}

union perf_event *
-perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)
+perf_mmap__read_backward(struct perf_mmap *md)
{
- struct perf_mmap *md = &evlist->mmap[idx];
u64 head, end;
u64 start = md->prev;

@@ -836,6 +835,31 @@ perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)
return perf_mmap__read(md, false, start, end, &md->prev);
}

+union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int idx)
+{
+ struct perf_mmap *md = &evlist->mmap[idx];
+
+ /*
+ * Check messup is required for forward overwritable ring buffer:
+ * memory pointed by md->prev can be overwritten in this case.
+ * No need for read-write ring buffer: kernel stop outputting when
+ * it hit md->prev (perf_mmap__consume()).
+ */
+ return perf_mmap__read_forward(md, evlist->overwrite);
+}
+
+union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)
+{
+ struct perf_mmap *md = &evlist->mmap[idx];
+
+ /*
+ * No need to check messup for backward ring buffer:
+ * We can always read arbitrary long data from a backward
+ * ring buffer unless we forget to pause it before reading.
+ */
+ return perf_mmap__read_backward(md);
+}
+
union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
{
if (!evlist->backward)
@@ -843,9 +867,8 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
return perf_evlist__mmap_read_backward(evlist, idx);
}

-void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx)
+void perf_mmap__read_catchup(struct perf_mmap *md)
{
- struct perf_mmap *md = &evlist->mmap[idx];
u64 head;

if (!atomic_read(&md->refcnt))
@@ -855,38 +878,54 @@ void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx)
md->prev = head;
}

+void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx)
+{
+ perf_mmap__read_catchup(&evlist->mmap[idx]);
+}
+
static bool perf_mmap__empty(struct perf_mmap *md)
{
return perf_mmap__read_head(md) == md->prev && !md->auxtrace_mmap.base;
}

-static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
+static void perf_mmap__get(struct perf_mmap *map)
{
- atomic_inc(&evlist->mmap[idx].refcnt);
+ atomic_inc(&map->refcnt);
}

-static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
+static void perf_mmap__put(struct perf_mmap *md)
{
- struct perf_mmap *md = &evlist->mmap[idx];
-
BUG_ON(md->base && atomic_read(&md->refcnt) == 0);

if (atomic_dec_and_test(&md->refcnt))
- __perf_evlist__munmap(evlist, idx);
+ perf_mmap__munmap(md);
}

-void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
+static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
{
- struct perf_mmap *md = &evlist->mmap[idx];
+ perf_mmap__get(&evlist->mmap[idx]);
+}
+
+static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
+{
+ perf_mmap__put(&evlist->mmap[idx]);
+}

- if (!evlist->overwrite) {
+void perf_mmap__consume(struct perf_mmap *md, bool overwrite)
+{
+ if (!overwrite) {
u64 old = md->prev;

perf_mmap__write_tail(md, old);
}

if (atomic_read(&md->refcnt) == 1 && perf_mmap__empty(md))
- perf_evlist__mmap_put(evlist, idx);
+ perf_mmap__put(md);
+}
+
+void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
+{
+ perf_mmap__consume(&evlist->mmap[idx], evlist->overwrite);
}

int __weak auxtrace_mmap__mmap(struct auxtrace_mmap *mm __maybe_unused,
@@ -917,15 +956,20 @@ void __weak auxtrace_mmap_params__set_idx(
{
}

-static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx)
+static void perf_mmap__munmap(struct perf_mmap *map)
{
- if (evlist->mmap[idx].base != NULL) {
- munmap(evlist->mmap[idx].base, evlist->mmap_len);
- evlist->mmap[idx].base = NULL;
- evlist->mmap[idx].fd = -1;
- atomic_set(&evlist->mmap[idx].refcnt, 0);
+ if (map->base != NULL) {
+ munmap(map->base, perf_mmap__mmap_len(map));
+ map->base = NULL;
+ map->fd = -1;
+ atomic_set(&map->refcnt, 0);
}
- auxtrace_mmap__munmap(&evlist->mmap[idx].auxtrace_mmap);
+ auxtrace_mmap__munmap(&map->auxtrace_mmap);
+}
+
+static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx)
+{
+ perf_mmap__munmap(&evlist->mmap[idx]);
}

void perf_evlist__munmap(struct perf_evlist *evlist)
@@ -941,20 +985,21 @@ void perf_evlist__munmap(struct perf_evlist *evlist)
zfree(&evlist->mmap);
}

-static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
+static struct perf_mmap *perf_evlist__alloc_mmap(struct perf_evlist *evlist)
{
int i;
+ struct perf_mmap *map;

evlist->nr_mmaps = cpu_map__nr(evlist->cpus);
if (cpu_map__empty(evlist->cpus))
evlist->nr_mmaps = thread_map__nr(evlist->threads);
- evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
- if (!evlist->mmap)
- return -ENOMEM;
+ map = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
+ if (!map)
+ return NULL;

for (i = 0; i < evlist->nr_mmaps; i++)
- evlist->mmap[i].fd = -1;
- return 0;
+ map[i].fd = -1;
+ return map;
}

struct mmap_params {
@@ -963,8 +1008,8 @@ struct mmap_params {
struct auxtrace_mmap_params auxtrace_mp;
};

-static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
- struct mmap_params *mp, int fd)
+static int perf_mmap__mmap(struct perf_mmap *map,
+ struct mmap_params *mp, int fd)
{
/*
* The last one will be done at perf_evlist__mmap_consume(), so that we
@@ -979,26 +1024,32 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
* evlist layer can't just drop it when filtering events in
* perf_evlist__filter_pollfd().
*/
- atomic_set(&evlist->mmap[idx].refcnt, 2);
- evlist->mmap[idx].prev = 0;
- evlist->mmap[idx].mask = mp->mask;
- evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, mp->prot,
- MAP_SHARED, fd, 0);
- if (evlist->mmap[idx].base == MAP_FAILED) {
+ atomic_set(&map->refcnt, 2);
+ map->prev = 0;
+ map->mask = mp->mask;
+ map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
+ MAP_SHARED, fd, 0);
+ if (map->base == MAP_FAILED) {
pr_debug2("failed to mmap perf event ring buffer, error %d\n",
errno);
- evlist->mmap[idx].base = NULL;
+ map->base = NULL;
return -1;
}
- evlist->mmap[idx].fd = fd;
+ map->fd = fd;

- if (auxtrace_mmap__mmap(&evlist->mmap[idx].auxtrace_mmap,
- &mp->auxtrace_mp, evlist->mmap[idx].base, fd))
+ if (auxtrace_mmap__mmap(&map->auxtrace_mmap,
+ &mp->auxtrace_mp, map->base, fd))
return -1;

return 0;
}

+static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
+ struct mmap_params *mp, int fd)
+{
+ return perf_mmap__mmap(&evlist->mmap[idx], mp, fd);
+}
+
static bool
perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
struct perf_evsel *evsel)
@@ -1248,7 +1299,9 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
.prot = PROT_READ | (overwrite ? 0 : PROT_WRITE),
};

- if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
+ if (!evlist->mmap)
+ evlist->mmap = perf_evlist__alloc_mmap(evlist);
+ if (!evlist->mmap)
return -ENOMEM;

if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index afd0877..9e680c6 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -35,6 +35,12 @@ struct perf_mmap {
char event_copy[PERF_SAMPLE_MAX_SIZE] __attribute__((aligned(8)));
};

+static inline size_t
+perf_mmap__mmap_len(struct perf_mmap *map)
+{
+ return map->mask + 1 + page_size;
+}
+
struct perf_evlist {
struct list_head entries;
struct hlist_head heads[PERF_EVLIST__HLIST_SIZE];
@@ -129,6 +135,12 @@ struct perf_evsel *perf_evlist__id2evsel_strict(struct perf_evlist *evlist,

struct perf_sample_id *perf_evlist__id2sid(struct perf_evlist *evlist, u64 id);

+union perf_event *perf_mmap__read_forward(struct perf_mmap *map, bool check_messup);
+union perf_event *perf_mmap__read_backward(struct perf_mmap *map);
+
+void perf_mmap__read_catchup(struct perf_mmap *md);
+void perf_mmap__consume(struct perf_mmap *md, bool overwrite);
+
union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx);

union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist,
--
1.8.3.4
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