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Groups > linux.kernel > #1441216 > unrolled thread

[PATCH v15 00/12] perf tools: Support overwritable ring buffer

Started byWang Nan <wangnan0@huawei.com>
First post2016-07-12 12:10 +0200
Last post2016-07-14 04:00 +0200
Articles 5 — 3 participants

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Contents

  [PATCH v15 00/12] perf tools: Support overwritable ring buffer Wang Nan <wangnan0@huawei.com> - 2016-07-12 12:10 +0200
    [PATCH v15 01/12] perf tools: Drop redundant evsel->overwrite indicator Wang Nan <wangnan0@huawei.com> - 2016-07-12 12:10 +0200
    [PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers Wang Nan <wangnan0@huawei.com> - 2016-07-12 12:10 +0200
      Re: [PATCH v15 03/12] perf tools: Update perf evlist mmap related  APIs and helpers Jiri Olsa <jolsa@redhat.com> - 2016-07-13 16:10 +0200
        Re: [PATCH v15 03/12] perf tools: Update perf evlist mmap related  APIs and helpers "Wangnan (F)" <wangnan0@huawei.com> - 2016-07-14 04:00 +0200

#1441216 — [PATCH v15 00/12] perf tools: Support overwritable ring buffer

FromWang Nan <wangnan0@huawei.com>
Date2016-07-12 12:10 +0200
Subject[PATCH v15 00/12] perf tools: Support overwritable ring buffer
Message-ID<rU2NA-3tA-5@gated-at.bofh.it>
This patch set enables daemonized perf recording by utilizing
overwritable backward ring buffer. With this feature one can
put perf background, and dump ring buffer records by a SIGUSR2
when he/she find something unusual. For example, following
command record system calls, schedule events and samples on cpu cycles
continously:

 # perf record -g -e cycles -e raw_syscalls:*/call-graph=no/ \
                  -e sched:sched_switch/call-graph=no/ \
                  --switch-output --overwrite -a

Then by sending SIGUSR2 to perf when lagging is happen, we get multiple
perf.data output, each of them correspond a abnormal event, and the data
size is reasonable:

 # ls -l ./perf.data*
 -rw------- 1 root root 5122165 May 13 23:51 ./perf.data.2016051323511683
 -rw------- 1 root root 5135093 May 13 23:51 ./perf.data.2016051323512107
 -rw------- 1 root root 5135213 May 13 23:51 ./perf.data.2016051323512215
 -rw------- 1 root root 5135157 May 13 23:51 ./perf.data.2016051323512387

v1 -> v2: Totally redesign: drop the principle of 'channal', use
          auxiliary evlist instead. Fix missing documentation.

v2 -> v3: Rename perf_evlist__toggle_paused() to perf_evlist__pause/resume.

v3 -> v4: Update commit message to describe auxiliary evlist more clearly.

v4 -> v5: Reorder commits, ensure '--overwrite' works right after perf
          support the option.
          Add test cases for auxiliary evlist.
          Avoid bug if main evlist is empty.

v5 -> v6: Improve filter pollfd related code.

v6 -> v7: Rebase to newest perf/core.

v7 -> v8: Unmap mmaps from parent and children in
          perf_evlist__munmap_filtered(), hide more detail of aux evlist.
          Add --tail-synthesize, do synthesize at the end of perf.data.

v8 -> v9: Beautify code of test case, make patch set more granular,
          improve documentation.

v9 -> v10: Make patch set more granular: extract preparation code to
           patch 1-3.

v10 -> v11: Rebase to newest perf/core: solve conflicts caused by commit
            e5cadb93d08 ("perf evlist: Rename for_each() macros to
            for_each_entry()").

v11 -> v12: Improve 'perf test backward': skip this test on old kernel,
            resolve conflicts.

v12 -> v13: Drop evsel->overwrite, use evsel->attr.write_backward instead.

v13 -> v14: Follow Jiri Olsa's suggestion: Improve commit message,
            add OVERWRITE_EVT_NOTREADY state, stop the state machine if
	    overwrite_evlist is not generated.

v15 -> v16: Totally redesign: drop auxiliary evlist, use one evlist to
            contain normal and backward ring buffers (add evlist->backward_mmap).
            Build new API and helpers for it.

Arnaldo Carvalho de Melo (1):
  perf tools: Drop redundant evsel->overwrite indicator

Wang Nan (11):
  tools lib fd array: Allow associating a pointer cookie with each entry
  perf tools: Update perf evlist mmap related APIs and helpers
  perf tools: Record mmap cookie into fdarray private field
  perf tools: Extract common code in mmap failure processing
  perf tools: Alloc backward_mmap array for evlist
  perf tools: Map backward events to backward_mmap
  perf tools: Drop evlist->backward
  perf record: Read from overwritable ring buffer
  perf tools: Enable overwrite settings
  perf tools: Don't warn about out of order event if write_backward is
    used
  perf tools: Add --tail-synthesize option

 tools/lib/api/fd/array.h                 |   1 +
 tools/perf/Documentation/perf-record.txt |  22 ++++
 tools/perf/builtin-record.c              | 198 +++++++++++++++++++++++++++----
 tools/perf/perf.h                        |   2 +
 tools/perf/tests/backward-ring-buffer.c  |  14 +--
 tools/perf/util/evlist.c                 | 186 +++++++++++++++++------------
 tools/perf/util/evlist.h                 |  13 +-
 tools/perf/util/evsel.c                  |  16 +--
 tools/perf/util/evsel.h                  |   3 +-
 tools/perf/util/parse-events.c           |  20 +++-
 tools/perf/util/parse-events.h           |   2 +
 tools/perf/util/parse-events.l           |   2 +
 tools/perf/util/session.c                |  22 +++-
 13 files changed, 383 insertions(+), 118 deletions(-)

-- 
1.8.3.4

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#1441217 — [PATCH v15 01/12] perf tools: Drop redundant evsel->overwrite indicator

FromWang Nan <wangnan0@huawei.com>
Date2016-07-12 12:10 +0200
Subject[PATCH v15 01/12] perf tools: Drop redundant evsel->overwrite indicator
Message-ID<rU2NC-3tA-71@gated-at.bofh.it>
In reply to#1441216
From: Arnaldo Carvalho de Melo <acme@redhat.com>

evsel->overwrite indicator means an event should be put into
overwritable ring buffer. In current implementation, it equals to
evsel->attr.write_backward. To reduce compliexity, remove
evsel->overwrite, use evsel->attr.write_backward instead.

In addition, in __perf_evsel__open(), if kernel doesn't support
write_backward and user explicitly set it in evsel, don't fallback
like other missing feature, since it is meaningless to fall back to
a forward ring buffer in this case: we are unable to stably read
from an forward overwritable ring buffer.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Wang Nan <wangnan0@huawei.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/tests/backward-ring-buffer.c |  1 +
 tools/perf/util/evlist.c                |  4 ++--
 tools/perf/util/evsel.c                 | 12 +++++-------
 tools/perf/util/evsel.h                 |  1 -
 4 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
index e70313f..1750ef2 100644
--- a/tools/perf/tests/backward-ring-buffer.c
+++ b/tools/perf/tests/backward-ring-buffer.c
@@ -101,6 +101,7 @@ int test__backward_ring_buffer(int subtest __maybe_unused)
 		return TEST_FAIL;
 	}
 
+	evlist->backward = true;
 	err = perf_evlist__create_maps(evlist, &opts.target);
 	if (err < 0) {
 		pr_debug("Not enough memory to create thread/cpu maps\n");
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 1135077..7228596 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1003,7 +1003,7 @@ static bool
 perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
 			 struct perf_evsel *evsel)
 {
-	if (evsel->overwrite)
+	if (evsel->attr.write_backward)
 		return false;
 	return true;
 }
@@ -1018,7 +1018,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 	evlist__for_each_entry(evlist, evsel) {
 		int fd;
 
-		if (evsel->overwrite != (evlist->overwrite && evlist->backward))
+		if (!!evsel->attr.write_backward != (evlist->overwrite && evlist->backward))
 			continue;
 
 		if (evsel->system_wide && thread)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 0fea724..3abe519 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1359,6 +1359,9 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
 	int pid = -1, err;
 	enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;
 
+	if (perf_missing_features.write_backward && evsel->attr.write_backward)
+		return -EINVAL;
+
 	if (evsel->system_wide)
 		nthreads = 1;
 	else
@@ -1389,11 +1392,6 @@ fallback_missing_features:
 	if (perf_missing_features.lbr_flags)
 		evsel->attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
 				     PERF_SAMPLE_BRANCH_NO_CYCLES);
-	if (perf_missing_features.write_backward) {
-		if (evsel->overwrite)
-			return -EINVAL;
-		evsel->attr.write_backward = false;
-	}
 retry_sample_id:
 	if (perf_missing_features.sample_id_all)
 		evsel->attr.sample_id_all = 0;
@@ -1495,7 +1493,7 @@ try_fallback:
 	 */
 	if (!perf_missing_features.write_backward && evsel->attr.write_backward) {
 		perf_missing_features.write_backward = true;
-		goto fallback_missing_features;
+		goto out_close;
 	} else if (!perf_missing_features.clockid_wrong && evsel->attr.use_clockid) {
 		perf_missing_features.clockid_wrong = true;
 		goto fallback_missing_features;
@@ -2404,7 +2402,7 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
 	"We found oprofile daemon running, please stop it and try again.");
 		break;
 	case EINVAL:
-		if (evsel->overwrite && perf_missing_features.write_backward)
+		if (evsel->attr.write_backward && perf_missing_features.write_backward)
 			return scnprintf(msg, size, "Reading from overwrite event is not supported by this kernel.");
 		if (perf_missing_features.clockid)
 			return scnprintf(msg, size, "clockid feature not supported.");
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 86fed7a..a31ee2d 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -114,7 +114,6 @@ struct perf_evsel {
 	bool			tracking;
 	bool			per_pkg;
 	bool			precise_max;
-	bool			overwrite;
 	/* parse modifier helper */
 	int			exclude_GH;
 	int			nr_members;
-- 
1.8.3.4

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#1441218 — [PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers

FromWang Nan <wangnan0@huawei.com>
Date2016-07-12 12:10 +0200
Subject[PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers
Message-ID<rU2NC-3tA-69@gated-at.bofh.it>
In reply to#1441216
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 a evlist contain only one mmap array.

Following commits are going to introduce multiple mmap array to evlist.
This patch refators those APIs and helpers, extracts functions accept
perf_mmap pointer directly. New helpers and APIs are decoupled with
perf_evlist, and become perf_mmap functions.

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 | 128 +++++++++++++++++++++++++++++++----------------
 tools/perf/util/evlist.h |  11 ++++
 2 files changed, 96 insertions(+), 43 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 7228596..49f1d7c 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 overwrite)
 {
-	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, overwrite, 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, bool overwrite __maybe_unused)
 {
-	struct perf_mmap *md = &evlist->mmap[idx];
 	u64 head, end;
 	u64 start = md->prev;
 
@@ -836,6 +835,20 @@ 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];
+
+	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];
+
+	return perf_mmap__read_backward(md, evlist->overwrite);
+}
+
 union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
 {
 	if (!evlist->backward)
@@ -843,9 +856,8 @@ 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 +867,54 @@ 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]);
+}
 
-	if (!evlist->overwrite) {
+static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
+{
+	perf_mmap__put(&evlist->mmap[idx]);
+}
+
+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 +945,20 @@ 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 +974,21 @@ 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 +997,8 @@ 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 +1013,32 @@ 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 +1288,9 @@ 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 872912b..2fc5c16 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 +135,11 @@ 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 overwrite);
+union perf_event *perf_mmap__read_backward(struct perf_mmap *map, bool overwrite);
+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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#1442494 — Re: [PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers

FromJiri Olsa <jolsa@redhat.com>
Date2016-07-13 16:10 +0200
SubjectRe: [PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers
Message-ID<rUt1o-47M-21@gated-at.bofh.it>
In reply to#1441218
On Tue, Jul 12, 2016 at 10:00:03AM +0000, Wang Nan wrote:

SNIP

> -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 overwrite)
>  {
> -	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, overwrite, 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, bool overwrite __maybe_unused)
>  {
> -	struct perf_mmap *md = &evlist->mmap[idx];
>  	u64 head, end;
>  	u64 start = md->prev;
>  
> @@ -836,6 +835,20 @@ perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)
>  	return perf_mmap__read(md, false, start, end, &md->prev);

should you pas evlist->overwrite in here?

thanks,
jirka

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#1442989 — Re: [PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers

From"Wangnan (F)" <wangnan0@huawei.com>
Date2016-07-14 04:00 +0200
SubjectRe: [PATCH v15 03/12] perf tools: Update perf evlist mmap related APIs and helpers
Message-ID<rUE6t-2Rt-7@gated-at.bofh.it>
In reply to#1442494

On 2016/7/13 22:06, Jiri Olsa wrote:
> On Tue, Jul 12, 2016 at 10:00:03AM +0000, Wang Nan wrote:
>
> SNIP
>
>> -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 overwrite)
>>   {
>> -	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, overwrite, 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, bool overwrite __maybe_unused)
>>   {
>> -	struct perf_mmap *md = &evlist->mmap[idx];
>>   	u64 head, end;
>>   	u64 start = md->prev;
>>   
>> @@ -836,6 +835,20 @@ perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)
>>   	return perf_mmap__read(md, false, start, end, &md->prev);
> should you pas evlist->overwrite in here?

No need. The second arg of perf_mmap__read() is not 'overwrite', but 
'check_messup'.
When set to 'true', stop reading if caller require a buffer larger than 
half of the
size of the ring buffer and report a warning. Only forward, read-only 
ring buffer
requires this check. We can always read the whole backward ring buffer 
because we
pause it before reading.

I'll add more comments here.

Thank you.

> thanks,
> jirka

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