[PATCH 0/7] perf tools: Clarify overwrite and backward, bugfix

[PATCH 0/7] perf tools: Clarify overwrite and backward, bugfix

[Wang Nan]

Based on previous discussion, perf needs to support only two types
of ringbuffer: read-write + forward, readonly + backward. This patchset
completly removes the concept of 'overwrite' from code level, controls
mapping permission using write_backward instead.

Wang Nan (7):
  perf mmap: Fix perf backward recording
  perf tests: Set evlist of test__backward_ring_buffer() to !overwrite
  perf tests: Set evlist of test__sw_clock_freq() to !overwrite
  perf tests: Set evlist of test__basic_mmap() to !overwrite
  perf tests: Set evlist of test__task_exit() to !overwrite
  perf tools: Remove 'overwrite' concept from code level
  perf tools: Remove prot field in mmap param

 tools/perf/arch/x86/tests/perf-time-to-tsc.c |  2 +-
 tools/perf/builtin-kvm.c                     |  2 +-
 tools/perf/builtin-record.c                  |  4 ++--
 tools/perf/builtin-top.c                     |  2 +-
 tools/perf/builtin-trace.c                   |  2 +-
 tools/perf/tests/backward-ring-buffer.c      |  2 +-
 tools/perf/tests/bpf.c                       |  2 +-
 tools/perf/tests/code-reading.c              |  2 +-
 tools/perf/tests/keep-tracking.c             |  2 +-
 tools/perf/tests/mmap-basic.c                |  2 +-
 tools/perf/tests/openat-syscall-tp-fields.c  |  2 +-
 tools/perf/tests/perf-record.c               |  2 +-
 tools/perf/tests/sw-clock.c                  |  2 +-
 tools/perf/tests/switch-tracking.c           |  2 +-
 tools/perf/tests/task-exit.c                 |  2 +-
 tools/perf/util/evlist.c                     | 21 ++++++++++-----------
 tools/perf/util/evlist.h                     |  6 ++----
 tools/perf/util/mmap.c                       | 10 +++++-----
 tools/perf/util/mmap.h                       |  6 +++---
 tools/perf/util/python.c                     | 10 +++++-----
 20 files changed, 41 insertions(+), 44 deletions(-)

-- 
2.10.1

[PATCH 1/7] perf mmap: Fix perf backward recording

[Wang Nan]

perf record backward recording doesn't work as we expected: it never
overwrite when ring buffer full.

Test:

(Run a busy printing task background like this:

 while True:
     print 123

send SIGUSR2 to perf to capture snapshot.)

 # ./perf record --overwrite -e raw_syscalls:sys_enter -e raw_syscalls:sys_exit --exclude-perf -a --switch-output
 [ perf record: dump data: Woken up 1 times ]
 [ perf record: Dump perf.data.2017110101520743 ]
 [ perf record: dump data: Woken up 1 times ]
 [ perf record: Dump perf.data.2017110101521251 ]
 [ perf record: dump data: Woken up 1 times ]
 [ perf record: Dump perf.data.2017110101521692 ]
 ^C[ perf record: Woken up 1 times to write data ]
 [ perf record: Dump perf.data.2017110101521936 ]
 [ perf record: Captured and wrote 0.826 MB perf.data.<timestamp> ]

 # ./perf script -i ./perf.data.2017110101520743 | head -n3
             perf  2717 [000] 12449.310785: raw_syscalls:sys_enter: NR 16 (5, 2400, 0, 59, 100, 0)
             perf  2717 [000] 12449.310790: raw_syscalls:sys_enter: NR 7 (4112340, 2, ffffffff, 3df, 100, 0)
           python  2545 [000] 12449.310800:  raw_syscalls:sys_exit: NR 1 = 4
 # ./perf script -i ./perf.data.2017110101521251 | head -n3
             perf  2717 [000] 12449.310785: raw_syscalls:sys_enter: NR 16 (5, 2400, 0, 59, 100, 0)
             perf  2717 [000] 12449.310790: raw_syscalls:sys_enter: NR 7 (4112340, 2, ffffffff, 3df, 100, 0)
           python  2545 [000] 12449.310800:  raw_syscalls:sys_exit: NR 1 = 4
 # ./perf script -i ./perf.data.2017110101521692 | head -n3
             perf  2717 [000] 12449.310785: raw_syscalls:sys_enter: NR 16 (5, 2400, 0, 59, 100, 0)
             perf  2717 [000] 12449.310790: raw_syscalls:sys_enter: NR 7 (4112340, 2, ffffffff, 3df, 100, 0)
           python  2545 [000] 12449.310800:  raw_syscalls:sys_exit: NR 1 = 4

Timestamps are never change, but my background task is a dead loop, can
easily overwhelme the ring buffer.

This patch fix it by force unsetting PROT_WRITE for backward ring
buffer, so all backward ring buffer become overwrite ring buffer.

Test result:

 # ./perf record --overwrite -e raw_syscalls:sys_enter -e raw_syscalls:sys_exit --exclude-perf -a --switch-output
 [ perf record: dump data: Woken up 1 times ]
 [ perf record: Dump perf.data.2017110101285323 ]
 [ perf record: dump data: Woken up 1 times ]
 [ perf record: Dump perf.data.2017110101290053 ]
 [ perf record: dump data: Woken up 1 times ]
 [ perf record: Dump perf.data.2017110101290446 ]
 ^C[ perf record: Woken up 1 times to write data ]
 [ perf record: Dump perf.data.2017110101290837 ]
 [ perf record: Captured and wrote 0.826 MB perf.data.<timestamp> ]
 # ./perf script -i ./perf.data.2017110101285323 | head -n3
           python  2545 [000] 11064.268083:  raw_syscalls:sys_exit: NR 1 = 4
           python  2545 [000] 11064.268084: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0)
           python  2545 [000] 11064.268086:  raw_syscalls:sys_exit: NR 1 = 4
 # ./perf script -i ./perf.data.2017110101290 | head -n3
 failed to open ./perf.data.2017110101290: No such file or directory
 # ./perf script -i ./perf.data.2017110101290053 | head -n3
           python  2545 [000] 11071.564062: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0)
           python  2545 [000] 11071.564064:  raw_syscalls:sys_exit: NR 1 = 4
           python  2545 [000] 11071.564066: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0)
 # ./perf script -i ./perf.data.2017110101290 | head -n3
 perf.data.2017110101290053  perf.data.2017110101290446  perf.data.2017110101290837
 # ./perf script -i ./perf.data.2017110101290446 | head -n3
             sshd  1321 [000] 11075.499473:  raw_syscalls:sys_exit: NR 14 = 0
             sshd  1321 [000] 11075.499474: raw_syscalls:sys_enter: NR 14 (2, 7ffe98899490, 0, 8, 0, 3000)
             sshd  1321 [000] 11075.499474:  raw_syscalls:sys_exit: NR 14 = 0
 # ./perf script -i ./perf.data.2017110101290837 | head -n3
           python  2545 [000] 11079.280844:  raw_syscalls:sys_exit: NR 1 = 4
           python  2545 [000] 11079.280847: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0)
           python  2545 [000] 11079.280850:  raw_syscalls:sys_exit: NR 1 = 4

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/util/evlist.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index c6c891e..4c5daba 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -799,22 +799,28 @@ perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
 }
 
 static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
-				       struct mmap_params *mp, int cpu_idx,
+				       struct mmap_params *_mp, int cpu_idx,
 				       int thread, int *_output, int *_output_backward)
 {
 	struct perf_evsel *evsel;
 	int revent;
 	int evlist_cpu = cpu_map__cpu(evlist->cpus, cpu_idx);
+	struct mmap_params *mp;
 
 	evlist__for_each_entry(evlist, evsel) {
 		struct perf_mmap *maps = evlist->mmap;
+		struct mmap_params rdonly_mp;
 		int *output = _output;
 		int fd;
 		int cpu;
 
+		mp = _mp;
 		if (evsel->attr.write_backward) {
 			output = _output_backward;
 			maps = evlist->backward_mmap;
+			rdonly_mp = *_mp;
+			rdonly_mp.prot &= ~PROT_WRITE;
+			mp = &rdonly_mp;
 
 			if (!maps) {
 				maps = perf_evlist__alloc_mmap(evlist);
-- 
2.10.1

[PATCH 2/7] perf tests: Set evlist of test__backward_ring_buffer() to !overwrite

[Wang Nan]

Setting overwrite in perf_evlist__mmap() is meaningless because the
event in this evlist is already have 'overwrite' postfix and goes to
backward ring buffer automatically. Pass 'false' to perf_evlist__mmap()
to make it similar to others.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/tests/backward-ring-buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
index d233ad3..992c917 100644
--- a/tools/perf/tests/backward-ring-buffer.c
+++ b/tools/perf/tests/backward-ring-buffer.c
@@ -58,7 +58,7 @@ static int do_test(struct perf_evlist *evlist, int mmap_pages,
 	int err;
 	char sbuf[STRERR_BUFSIZE];
 
-	err = perf_evlist__mmap(evlist, mmap_pages, true);
+	err = perf_evlist__mmap(evlist, mmap_pages, false);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
-- 
2.10.1

Re: [PATCH 2/7] perf tests: Set evlist of test__backward_ring_buffer() to !overwrite

[Arnaldo Carvalho de Melo]

Em Mon, Nov 13, 2017 at 01:38:04AM +0000, Wang Nan escreveu:
> Setting overwrite in perf_evlist__mmap() is meaningless because the
> event in this evlist is already have 'overwrite' postfix and goes to
> backward ring buffer automatically. Pass 'false' to perf_evlist__mmap()
> to make it similar to others.

applied
 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/tests/backward-ring-buffer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
> index d233ad3..992c917 100644
> --- a/tools/perf/tests/backward-ring-buffer.c
> +++ b/tools/perf/tests/backward-ring-buffer.c
> @@ -58,7 +58,7 @@ static int do_test(struct perf_evlist *evlist, int mmap_pages,
>  	int err;
>  	char sbuf[STRERR_BUFSIZE];
>  
> -	err = perf_evlist__mmap(evlist, mmap_pages, true);
> +	err = perf_evlist__mmap(evlist, mmap_pages, false);
>  	if (err < 0) {
>  		pr_debug("perf_evlist__mmap: %s\n",
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> -- 
> 2.10.1

[tip:perf/core] perf tests: Set evlist of test__backward_ring_buffer() to !overwrite

[tip-bot for Wang Nan]

Commit-ID:  d492326f160e44e08fcf132a63163b36dd8e8839
Gitweb:     https://git.kernel.org/tip/d492326f160e44e08fcf132a63163b36dd8e8839
Author:     Wang Nan <wangnan0@huawei.com>
AuthorDate: Mon, 13 Nov 2017 01:38:04 +0000
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 16 Nov 2017 14:49:57 -0300

perf tests: Set evlist of test__backward_ring_buffer() to !overwrite

Setting overwrite in perf_evlist__mmap() is meaningless because the
event in this evlist is already have 'overwrite' postfix and goes to
backward ring buffer automatically. Pass 'false' to perf_evlist__mmap()
to make it similar to others.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20171113013809.212417-3-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/backward-ring-buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
index 71b9a0b..43a8c6a 100644
--- a/tools/perf/tests/backward-ring-buffer.c
+++ b/tools/perf/tests/backward-ring-buffer.c
@@ -59,7 +59,7 @@ static int do_test(struct perf_evlist *evlist, int mmap_pages,
 	int err;
 	char sbuf[STRERR_BUFSIZE];
 
-	err = perf_evlist__mmap(evlist, mmap_pages, true);
+	err = perf_evlist__mmap(evlist, mmap_pages, false);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
 			 str_error_r(errno, sbuf, sizeof(sbuf)));

[PATCH 3/7] perf tests: Set evlist of test__sw_clock_freq() to !overwrite

[Wang Nan]

Unsetting overwrite when calling perf_evlist__mmap is harmless. This commit
passes false to it, makes following commits eliminate the overwrite argument
easier.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/tests/sw-clock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c
index d88511f..c468e6c 100644
--- a/tools/perf/tests/sw-clock.c
+++ b/tools/perf/tests/sw-clock.c
@@ -77,7 +77,7 @@ static int __test__sw_clock_freq(enum perf_sw_ids clock_id)
 		goto out_delete_evlist;
 	}
 
-	err = perf_evlist__mmap(evlist, 128, true);
+	err = perf_evlist__mmap(evlist, 128, false);
 	if (err < 0) {
 		pr_debug("failed to mmap event: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
-- 
2.10.1

Re: [PATCH 3/7] perf tests: Set evlist of test__sw_clock_freq() to !overwrite

[Arnaldo Carvalho de Melo]

Em Mon, Nov 13, 2017 at 01:38:05AM +0000, Wang Nan escreveu:
> Unsetting overwrite when calling perf_evlist__mmap is harmless. This commit
> passes false to it, makes following commits eliminate the overwrite argument
> easier.

applied
 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/tests/sw-clock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c
> index d88511f..c468e6c 100644
> --- a/tools/perf/tests/sw-clock.c
> +++ b/tools/perf/tests/sw-clock.c
> @@ -77,7 +77,7 @@ static int __test__sw_clock_freq(enum perf_sw_ids clock_id)
>  		goto out_delete_evlist;
>  	}
>  
> -	err = perf_evlist__mmap(evlist, 128, true);
> +	err = perf_evlist__mmap(evlist, 128, false);
>  	if (err < 0) {
>  		pr_debug("failed to mmap event: %d (%s)\n", errno,
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> -- 
> 2.10.1

[tip:perf/core] perf tests: Set evlist of test__sw_clock_freq() to !overwrite

[tip-bot for Wang Nan]

Commit-ID:  677b0601768881934f658bebb1713c3c843893fa
Gitweb:     https://git.kernel.org/tip/677b0601768881934f658bebb1713c3c843893fa
Author:     Wang Nan <wangnan0@huawei.com>
AuthorDate: Mon, 13 Nov 2017 01:38:05 +0000
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 16 Nov 2017 14:49:57 -0300

perf tests: Set evlist of test__sw_clock_freq() to !overwrite

Unsetting overwrite when calling perf_evlist__mmap is harmless. This
commit passes false to it, makes following commits eliminate the
overwrite argument easier.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20171113013809.212417-4-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/sw-clock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c
index 725a196..c6937ed 100644
--- a/tools/perf/tests/sw-clock.c
+++ b/tools/perf/tests/sw-clock.c
@@ -78,7 +78,7 @@ static int __test__sw_clock_freq(enum perf_sw_ids clock_id)
 		goto out_delete_evlist;
 	}
 
-	err = perf_evlist__mmap(evlist, 128, true);
+	err = perf_evlist__mmap(evlist, 128, false);
 	if (err < 0) {
 		pr_debug("failed to mmap event: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));

[PATCH 4/7] perf tests: Set evlist of test__basic_mmap() to !overwrite

[Wang Nan]

In this test, a large ring buffer is required so all events can feed into,
so overwrite or not is meaningless.

Change to !overwrite so following commits can remove this argument.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/tests/mmap-basic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/mmap-basic.c b/tools/perf/tests/mmap-basic.c
index bc8a70e..667d696 100644
--- a/tools/perf/tests/mmap-basic.c
+++ b/tools/perf/tests/mmap-basic.c
@@ -93,7 +93,7 @@ int test__basic_mmap(struct test *test __maybe_unused, int subtest __maybe_unuse
 		expected_nr_events[i] = 1 + rand() % 127;
 	}
 
-	if (perf_evlist__mmap(evlist, 128, true) < 0) {
+	if (perf_evlist__mmap(evlist, 128, false) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
-- 
2.10.1

Re: [PATCH 4/7] perf tests: Set evlist of test__basic_mmap() to !overwrite

[Arnaldo Carvalho de Melo]

Em Mon, Nov 13, 2017 at 01:38:06AM +0000, Wang Nan escreveu:
> In this test, a large ring buffer is required so all events can feed into,
> so overwrite or not is meaningless.
> 
> Change to !overwrite so following commits can remove this argument.

applied
 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/tests/mmap-basic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/mmap-basic.c b/tools/perf/tests/mmap-basic.c
> index bc8a70e..667d696 100644
> --- a/tools/perf/tests/mmap-basic.c
> +++ b/tools/perf/tests/mmap-basic.c
> @@ -93,7 +93,7 @@ int test__basic_mmap(struct test *test __maybe_unused, int subtest __maybe_unuse
>  		expected_nr_events[i] = 1 + rand() % 127;
>  	}
>  
> -	if (perf_evlist__mmap(evlist, 128, true) < 0) {
> +	if (perf_evlist__mmap(evlist, 128, false) < 0) {
>  		pr_debug("failed to mmap events: %d (%s)\n", errno,
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
>  		goto out_delete_evlist;
> -- 
> 2.10.1

[tip:perf/core] perf tests: Set evlist of test__basic_mmap() to !overwrite

[tip-bot for Wang Nan]

Commit-ID:  301d724aa19add1c0cf3ec8cad0d10151d30393f
Gitweb:     https://git.kernel.org/tip/301d724aa19add1c0cf3ec8cad0d10151d30393f
Author:     Wang Nan <wangnan0@huawei.com>
AuthorDate: Mon, 13 Nov 2017 01:38:06 +0000
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 16 Nov 2017 14:49:58 -0300

perf tests: Set evlist of test__basic_mmap() to !overwrite

In this test, a large ring buffer is required so all events can feed
into, so overwrite or not is meaningless.

Change to !overwrite so following commits can remove this argument.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20171113013809.212417-5-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/mmap-basic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/mmap-basic.c b/tools/perf/tests/mmap-basic.c
index 5a8bf31..91f10d6 100644
--- a/tools/perf/tests/mmap-basic.c
+++ b/tools/perf/tests/mmap-basic.c
@@ -94,7 +94,7 @@ int test__basic_mmap(struct test *test __maybe_unused, int subtest __maybe_unuse
 		expected_nr_events[i] = 1 + rand() % 127;
 	}
 
-	if (perf_evlist__mmap(evlist, 128, true) < 0) {
+	if (perf_evlist__mmap(evlist, 128, false) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;

[PATCH 5/7] perf tests: Set evlist of test__task_exit() to !overwrite

[Wang Nan]

Changing ringbuffer to !overwrite in this task is harmless because
this test uses a very low frequency (1) and using a very simple
program (true). There should have only 3 events in the whole test.
Overwriting is impossible to happen.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/tests/task-exit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c
index f0881d0..4fb6609 100644
--- a/tools/perf/tests/task-exit.c
+++ b/tools/perf/tests/task-exit.c
@@ -96,7 +96,7 @@ int test__task_exit(struct test *test __maybe_unused, int subtest __maybe_unused
 		goto out_delete_evlist;
 	}
 
-	if (perf_evlist__mmap(evlist, 128, true) < 0) {
+	if (perf_evlist__mmap(evlist, 128, false) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
-- 
2.10.1

Re: [PATCH 5/7] perf tests: Set evlist of test__task_exit() to !overwrite

[Arnaldo Carvalho de Melo]

Em Mon, Nov 13, 2017 at 01:38:07AM +0000, Wang Nan escreveu:
> Changing ringbuffer to !overwrite in this task is harmless because
> this test uses a very low frequency (1) and using a very simple
> program (true). There should have only 3 events in the whole test.
> Overwriting is impossible to happen.

applied
 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/tests/task-exit.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c
> index f0881d0..4fb6609 100644
> --- a/tools/perf/tests/task-exit.c
> +++ b/tools/perf/tests/task-exit.c
> @@ -96,7 +96,7 @@ int test__task_exit(struct test *test __maybe_unused, int subtest __maybe_unused
>  		goto out_delete_evlist;
>  	}
>  
> -	if (perf_evlist__mmap(evlist, 128, true) < 0) {
> +	if (perf_evlist__mmap(evlist, 128, false) < 0) {
>  		pr_debug("failed to mmap events: %d (%s)\n", errno,
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
>  		goto out_delete_evlist;
> -- 
> 2.10.1

[tip:perf/core] perf tests: Set evlist of test__task_exit() to !overwrite

[tip-bot for Wang Nan]

Commit-ID:  a0e3dd79cdd8ad838cbcefeff530a15193f8336e
Gitweb:     https://git.kernel.org/tip/a0e3dd79cdd8ad838cbcefeff530a15193f8336e
Author:     Wang Nan <wangnan0@huawei.com>
AuthorDate: Mon, 13 Nov 2017 01:38:07 +0000
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 16 Nov 2017 14:49:58 -0300

perf tests: Set evlist of test__task_exit() to !overwrite

Changing ringbuffer to !overwrite in this task is harmless because
this test uses a very low frequency (1) and using a very simple program
(true). There should have only 3 events in the whole test.  Overwriting
is impossible to happen.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20171113013809.212417-6-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/task-exit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c
index bc4a734..98c0984 100644
--- a/tools/perf/tests/task-exit.c
+++ b/tools/perf/tests/task-exit.c
@@ -97,7 +97,7 @@ int test__task_exit(struct test *test __maybe_unused, int subtest __maybe_unused
 		goto out_delete_evlist;
 	}
 
-	if (perf_evlist__mmap(evlist, 128, true) < 0) {
+	if (perf_evlist__mmap(evlist, 128, false) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;

[PATCH 6/7] perf tools: Remove 'overwrite' concept from code level

[Wang Nan]

Since all 'overwrite' usage are cleaned and no one really use a readonly main
ringbuffer, remove 'overwrite' from function arguments and evlist. The concept
of 'overwrite' and 'write_backward' are cleanner than before:

  1. In code level, there's no 'overwrite' concept. Each evlist has two
     ringbuffer groups. One is read-write/forward, another is readonly/backward.
     Don't support read-write/backward and readonly/forward.

  2. In user interface, we keep '--overwrite' and translate it into write_backward
     in each event.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/arch/x86/tests/perf-time-to-tsc.c |  2 +-
 tools/perf/builtin-kvm.c                     |  2 +-
 tools/perf/builtin-record.c                  |  4 ++--
 tools/perf/builtin-top.c                     |  2 +-
 tools/perf/builtin-trace.c                   |  2 +-
 tools/perf/tests/backward-ring-buffer.c      |  2 +-
 tools/perf/tests/bpf.c                       |  2 +-
 tools/perf/tests/code-reading.c              |  2 +-
 tools/perf/tests/keep-tracking.c             |  2 +-
 tools/perf/tests/mmap-basic.c                |  2 +-
 tools/perf/tests/openat-syscall-tp-fields.c  |  2 +-
 tools/perf/tests/perf-record.c               |  2 +-
 tools/perf/tests/sw-clock.c                  |  2 +-
 tools/perf/tests/switch-tracking.c           |  2 +-
 tools/perf/tests/task-exit.c                 |  2 +-
 tools/perf/util/evlist.c                     | 14 ++++++--------
 tools/perf/util/evlist.h                     |  6 ++----
 tools/perf/util/mmap.c                       |  6 +++---
 tools/perf/util/mmap.h                       |  2 +-
 tools/perf/util/python.c                     | 10 +++++-----
 20 files changed, 33 insertions(+), 37 deletions(-)

diff --git a/tools/perf/arch/x86/tests/perf-time-to-tsc.c b/tools/perf/arch/x86/tests/perf-time-to-tsc.c
index 5dd7efb..c7ea843 100644
--- a/tools/perf/arch/x86/tests/perf-time-to-tsc.c
+++ b/tools/perf/arch/x86/tests/perf-time-to-tsc.c
@@ -83,7 +83,7 @@ int test__perf_time_to_tsc(struct test *test __maybe_unused, int subtest __maybe
 
 	CHECK__(perf_evlist__open(evlist));
 
-	CHECK__(perf_evlist__mmap(evlist, UINT_MAX, false));
+	CHECK__(perf_evlist__mmap(evlist, UINT_MAX));
 
 	pc = evlist->mmap[0].base;
 	ret = perf_read_tsc_conversion(pc, &tc);
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 0af4c09..e3e2a80 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1043,7 +1043,7 @@ static int kvm_live_open_events(struct perf_kvm_stat *kvm)
 		goto out;
 	}
 
-	if (perf_evlist__mmap(evlist, kvm->opts.mmap_pages, false) < 0) {
+	if (perf_evlist__mmap(evlist, kvm->opts.mmap_pages) < 0) {
 		ui__error("Failed to mmap the events: %s\n",
 			  str_error_r(errno, sbuf, sizeof(sbuf)));
 		perf_evlist__close(evlist);
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f4d9fc5..b3ef33f 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -300,7 +300,7 @@ static int record__mmap_evlist(struct record *rec,
 	struct record_opts *opts = &rec->opts;
 	char msg[512];
 
-	if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, false,
+	if (perf_evlist__mmap_ex(evlist, opts->mmap_pages,
 				 opts->auxtrace_mmap_pages,
 				 opts->auxtrace_snapshot_mode) < 0) {
 		if (errno == EPERM) {
@@ -481,7 +481,7 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
 		struct auxtrace_mmap *mm = &maps[i].auxtrace_mmap;
 
 		if (maps[i].base) {
-			if (perf_mmap__push(&maps[i], evlist->overwrite, backward, rec, record__pushfn) != 0) {
+			if (perf_mmap__push(&maps[i], backward, rec, record__pushfn) != 0) {
 				rc = -1;
 				goto out;
 			}
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 477a869..83d2ae2 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -902,7 +902,7 @@ static int perf_top__start_counters(struct perf_top *top)
 		}
 	}
 
-	if (perf_evlist__mmap(evlist, opts->mmap_pages, false) < 0) {
+	if (perf_evlist__mmap(evlist, opts->mmap_pages) < 0) {
 		ui__error("Failed to mmap with %d (%s)\n",
 			    errno, str_error_r(errno, msg, sizeof(msg)));
 		goto out_err;
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index c373f9a..c3f2f98 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2404,7 +2404,7 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
 	if (err < 0)
 		goto out_error_apply_filters;
 
-	err = perf_evlist__mmap(evlist, trace->opts.mmap_pages, false);
+	err = perf_evlist__mmap(evlist, trace->opts.mmap_pages);
 	if (err < 0)
 		goto out_error_mmap;
 
diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
index 992c917..bdebcf9 100644
--- a/tools/perf/tests/backward-ring-buffer.c
+++ b/tools/perf/tests/backward-ring-buffer.c
@@ -58,7 +58,7 @@ static int do_test(struct perf_evlist *evlist, int mmap_pages,
 	int err;
 	char sbuf[STRERR_BUFSIZE];
 
-	err = perf_evlist__mmap(evlist, mmap_pages, false);
+	err = perf_evlist__mmap(evlist, mmap_pages);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
index 34c22cd..c433dd3 100644
--- a/tools/perf/tests/bpf.c
+++ b/tools/perf/tests/bpf.c
@@ -167,7 +167,7 @@ static int do_test(struct bpf_object *obj, int (*func)(void),
 		goto out_delete_evlist;
 	}
 
-	err = perf_evlist__mmap(evlist, opts.mmap_pages, false);
+	err = perf_evlist__mmap(evlist, opts.mmap_pages);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 466a462..b6c813e 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -638,7 +638,7 @@ static int do_test_code_reading(bool try_kcore)
 		break;
 	}
 
-	ret = perf_evlist__mmap(evlist, UINT_MAX, false);
+	ret = perf_evlist__mmap(evlist, UINT_MAX);
 	if (ret < 0) {
 		pr_debug("perf_evlist__mmap failed\n");
 		goto out_put;
diff --git a/tools/perf/tests/keep-tracking.c b/tools/perf/tests/keep-tracking.c
index 7394286..b282916 100644
--- a/tools/perf/tests/keep-tracking.c
+++ b/tools/perf/tests/keep-tracking.c
@@ -94,7 +94,7 @@ int test__keep_tracking(struct test *test __maybe_unused, int subtest __maybe_un
 		goto out_err;
 	}
 
-	CHECK__(perf_evlist__mmap(evlist, UINT_MAX, false));
+	CHECK__(perf_evlist__mmap(evlist, UINT_MAX));
 
 	/*
 	 * First, test that a 'comm' event can be found when the event is
diff --git a/tools/perf/tests/mmap-basic.c b/tools/perf/tests/mmap-basic.c
index 667d696..f43d862 100644
--- a/tools/perf/tests/mmap-basic.c
+++ b/tools/perf/tests/mmap-basic.c
@@ -93,7 +93,7 @@ int test__basic_mmap(struct test *test __maybe_unused, int subtest __maybe_unuse
 		expected_nr_events[i] = 1 + rand() % 127;
 	}
 
-	if (perf_evlist__mmap(evlist, 128, false) < 0) {
+	if (perf_evlist__mmap(evlist, 128) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
diff --git a/tools/perf/tests/openat-syscall-tp-fields.c b/tools/perf/tests/openat-syscall-tp-fields.c
index b6ee1c4..f68d818 100644
--- a/tools/perf/tests/openat-syscall-tp-fields.c
+++ b/tools/perf/tests/openat-syscall-tp-fields.c
@@ -63,7 +63,7 @@ int test__syscall_openat_tp_fields(struct test *test __maybe_unused, int subtest
 		goto out_delete_evlist;
 	}
 
-	err = perf_evlist__mmap(evlist, UINT_MAX, false);
+	err = perf_evlist__mmap(evlist, UINT_MAX);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
diff --git a/tools/perf/tests/perf-record.c b/tools/perf/tests/perf-record.c
index 19b6500..f9fbd8b 100644
--- a/tools/perf/tests/perf-record.c
+++ b/tools/perf/tests/perf-record.c
@@ -140,7 +140,7 @@ int test__PERF_RECORD(struct test *test __maybe_unused, int subtest __maybe_unus
 	 * fds in the same CPU to be injected in the same mmap ring buffer
 	 * (using ioctl(PERF_EVENT_IOC_SET_OUTPUT)).
 	 */
-	err = perf_evlist__mmap(evlist, opts.mmap_pages, false);
+	err = perf_evlist__mmap(evlist, opts.mmap_pages);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c
index c468e6c..fd01b24 100644
--- a/tools/perf/tests/sw-clock.c
+++ b/tools/perf/tests/sw-clock.c
@@ -77,7 +77,7 @@ static int __test__sw_clock_freq(enum perf_sw_ids clock_id)
 		goto out_delete_evlist;
 	}
 
-	err = perf_evlist__mmap(evlist, 128, false);
+	err = perf_evlist__mmap(evlist, 128);
 	if (err < 0) {
 		pr_debug("failed to mmap event: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
diff --git a/tools/perf/tests/switch-tracking.c b/tools/perf/tests/switch-tracking.c
index 2acd785..9fee2a0 100644
--- a/tools/perf/tests/switch-tracking.c
+++ b/tools/perf/tests/switch-tracking.c
@@ -448,7 +448,7 @@ int test__switch_tracking(struct test *test __maybe_unused, int subtest __maybe_
 		goto out;
 	}
 
-	err = perf_evlist__mmap(evlist, UINT_MAX, false);
+	err = perf_evlist__mmap(evlist, UINT_MAX);
 	if (err) {
 		pr_debug("perf_evlist__mmap failed!\n");
 		goto out_err;
diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c
index 4fb6609..4ba5a27 100644
--- a/tools/perf/tests/task-exit.c
+++ b/tools/perf/tests/task-exit.c
@@ -96,7 +96,7 @@ int test__task_exit(struct test *test __maybe_unused, int subtest __maybe_unused
 		goto out_delete_evlist;
 	}
 
-	if (perf_evlist__mmap(evlist, 128, false) < 0) {
+	if (perf_evlist__mmap(evlist, 128) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 4c5daba..4948d3d 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -711,7 +711,7 @@ union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int
 	 * 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);
+	return perf_mmap__read_forward(md, false);
 }
 
 union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)
@@ -738,7 +738,7 @@ void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx)
 
 void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
 {
-	perf_mmap__consume(&evlist->mmap[idx], evlist->overwrite);
+	perf_mmap__consume(&evlist->mmap[idx], false);
 }
 
 static void perf_evlist__munmap_nofree(struct perf_evlist *evlist)
@@ -1058,14 +1058,14 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
  * Return: %0 on success, negative error code otherwise.
  */
 int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
-			 bool overwrite, unsigned int auxtrace_pages,
+			 unsigned int auxtrace_pages,
 			 bool auxtrace_overwrite)
 {
 	struct perf_evsel *evsel;
 	const struct cpu_map *cpus = evlist->cpus;
 	const struct thread_map *threads = evlist->threads;
 	struct mmap_params mp = {
-		.prot = PROT_READ | (overwrite ? 0 : PROT_WRITE),
+		.prot = PROT_READ | PROT_WRITE,
 	};
 
 	if (!evlist->mmap)
@@ -1076,7 +1076,6 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 	if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
 		return -ENOMEM;
 
-	evlist->overwrite = overwrite;
 	evlist->mmap_len = perf_evlist__mmap_size(pages);
 	pr_debug("mmap size %zuB\n", evlist->mmap_len);
 	mp.mask = evlist->mmap_len - page_size - 1;
@@ -1097,10 +1096,9 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 	return perf_evlist__mmap_per_cpu(evlist, &mp);
 }
 
-int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
-		      bool overwrite)
+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages)
 {
-	return perf_evlist__mmap_ex(evlist, pages, overwrite, 0, false);
+	return perf_evlist__mmap_ex(evlist, pages, 0, false);
 }
 
 int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target)
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 8c433e9..1dd3291 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -30,7 +30,6 @@ struct perf_evlist {
 	int		 nr_entries;
 	int		 nr_groups;
 	int		 nr_mmaps;
-	bool		 overwrite;
 	bool		 enabled;
 	bool		 has_user_cpus;
 	size_t		 mmap_len;
@@ -168,10 +167,9 @@ int perf_evlist__parse_mmap_pages(const struct option *opt,
 unsigned long perf_event_mlock_kb_in_pages(void);
 
 int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
-			 bool overwrite, unsigned int auxtrace_pages,
+			 unsigned int auxtrace_pages,
 			 bool auxtrace_overwrite);
-int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
-		      bool overwrite);
+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages);
 void perf_evlist__munmap(struct perf_evlist *evlist);
 
 size_t perf_evlist__mmap_size(unsigned long pages);
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 9fe5f9c..703ed41 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -299,7 +299,7 @@ static int rb_find_range(void *data, int mask, u64 head, u64 old,
 	return backward_rb_find_range(data, mask, head, start, end);
 }
 
-int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool backward,
+int perf_mmap__push(struct perf_mmap *md, bool backward,
 		    void *to, int push(void *to, void *buf, size_t size))
 {
 	u64 head = perf_mmap__read_head(md);
@@ -321,7 +321,7 @@ int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool backward,
 		WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
 
 		md->prev = head;
-		perf_mmap__consume(md, overwrite || backward);
+		perf_mmap__consume(md, backward);
 		return 0;
 	}
 
@@ -346,7 +346,7 @@ int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool backward,
 	}
 
 	md->prev = head;
-	perf_mmap__consume(md, overwrite || backward);
+	perf_mmap__consume(md, backward);
 out:
 	return rc;
 }
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index efd78b8..2c3d291 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -89,7 +89,7 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
 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);
 
-int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool backward,
+int perf_mmap__push(struct perf_mmap *md, bool backward,
 		    void *to, int push(void *to, void *buf, size_t size));
 
 size_t perf_mmap__mmap_len(struct perf_mmap *map);
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index c129e99..ece33b4 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -856,14 +856,14 @@ static PyObject *pyrf_evlist__mmap(struct pyrf_evlist *pevlist,
 				   PyObject *args, PyObject *kwargs)
 {
 	struct perf_evlist *evlist = &pevlist->evlist;
-	static char *kwlist[] = { "pages", "overwrite", NULL };
-	int pages = 128, overwrite = false;
+	static char *kwlist[] = { "pages", NULL };
+	int pages = 128;
 
-	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ii", kwlist,
-					 &pages, &overwrite))
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|i", kwlist,
+					 &pages))
 		return NULL;
 
-	if (perf_evlist__mmap(evlist, pages, overwrite) < 0) {
+	if (perf_evlist__mmap(evlist, pages) < 0) {
 		PyErr_SetFromErrno(PyExc_OSError);
 		return NULL;
 	}
-- 
2.10.1

Re: [PATCH 6/7] perf tools: Remove 'overwrite' concept from code level

[Jiri Olsa]

On Mon, Nov 13, 2017 at 01:38:08AM +0000, Wang Nan wrote:

SNIP

>  size_t perf_mmap__mmap_len(struct perf_mmap *map);
> diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
> index c129e99..ece33b4 100644
> --- a/tools/perf/util/python.c
> +++ b/tools/perf/util/python.c
> @@ -856,14 +856,14 @@ static PyObject *pyrf_evlist__mmap(struct pyrf_evlist *pevlist,
>  				   PyObject *args, PyObject *kwargs)
>  {
>  	struct perf_evlist *evlist = &pevlist->evlist;
> -	static char *kwlist[] = { "pages", "overwrite", NULL };

unlikely, but there might be already some users of this..

I think the best would be to keep the "overwrite" here and
don't use it.. maybe warn or update docs, if there's any ;-)

jirka

> -	int pages = 128, overwrite = false;
> +	static char *kwlist[] = { "pages", NULL };
> +	int pages = 128;
>  
> -	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ii", kwlist,
> -					 &pages, &overwrite))
> +	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|i", kwlist,
> +					 &pages))
>  		return NULL;
>  
> -	if (perf_evlist__mmap(evlist, pages, overwrite) < 0) {
> +	if (perf_evlist__mmap(evlist, pages) < 0) {
>  		PyErr_SetFromErrno(PyExc_OSError);
>  		return NULL;
>  	}
> -- 
> 2.10.1
> 

RE: [PATCH 6/7] perf tools: Remove 'overwrite' concept from code level

[Liang, Kan]

> Since all 'overwrite' usage are cleaned and no one really use a readonly main
> ringbuffer, remove 'overwrite' from function arguments and evlist. The
> concept
> of 'overwrite' and 'write_backward' are cleanner than before:
> 
>   1. In code level, there's no 'overwrite' concept. Each evlist has two
>      ringbuffer groups. One is read-write/forward, another is
> readonly/backward.
>      Don't support read-write/backward and readonly/forward.
> 
>   2. In user interface, we keep '--overwrite' and translate it into
> write_backward
>      in each event.
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/arch/x86/tests/perf-time-to-tsc.c |  2 +-
>  tools/perf/builtin-kvm.c                     |  2 +-
>  tools/perf/builtin-record.c                  |  4 ++--
>  tools/perf/builtin-top.c                     |  2 +-
>  tools/perf/builtin-trace.c                   |  2 +-
>  tools/perf/tests/backward-ring-buffer.c      |  2 +-
>  tools/perf/tests/bpf.c                       |  2 +-
>  tools/perf/tests/code-reading.c              |  2 +-
>  tools/perf/tests/keep-tracking.c             |  2 +-
>  tools/perf/tests/mmap-basic.c                |  2 +-
>  tools/perf/tests/openat-syscall-tp-fields.c  |  2 +-
>  tools/perf/tests/perf-record.c               |  2 +-
>  tools/perf/tests/sw-clock.c                  |  2 +-
>  tools/perf/tests/switch-tracking.c           |  2 +-
>  tools/perf/tests/task-exit.c                 |  2 +-
>  tools/perf/util/evlist.c                     | 14 ++++++--------
>  tools/perf/util/evlist.h                     |  6 ++----
>  tools/perf/util/mmap.c                       |  6 +++---
>  tools/perf/util/mmap.h                       |  2 +-
>  tools/perf/util/python.c                     | 10 +++++-----
>  20 files changed, 33 insertions(+), 37 deletions(-)
> 
> diff --git a/tools/perf/arch/x86/tests/perf-time-to-tsc.c
> b/tools/perf/arch/x86/tests/perf-time-to-tsc.c
> index 5dd7efb..c7ea843 100644
> --- a/tools/perf/arch/x86/tests/perf-time-to-tsc.c
> +++ b/tools/perf/arch/x86/tests/perf-time-to-tsc.c
> @@ -83,7 +83,7 @@ int test__perf_time_to_tsc(struct test *test
> __maybe_unused, int subtest __maybe
> 
>  	CHECK__(perf_evlist__open(evlist));
> 
> -	CHECK__(perf_evlist__mmap(evlist, UINT_MAX, false));
> +	CHECK__(perf_evlist__mmap(evlist, UINT_MAX));
> 
>  	pc = evlist->mmap[0].base;
>  	ret = perf_read_tsc_conversion(pc, &tc);
> diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
> index 0af4c09..e3e2a80 100644
> --- a/tools/perf/builtin-kvm.c
> +++ b/tools/perf/builtin-kvm.c
> @@ -1043,7 +1043,7 @@ static int kvm_live_open_events(struct
> perf_kvm_stat *kvm)
>  		goto out;
>  	}
> 
> -	if (perf_evlist__mmap(evlist, kvm->opts.mmap_pages, false) < 0) {
> +	if (perf_evlist__mmap(evlist, kvm->opts.mmap_pages) < 0) {
>  		ui__error("Failed to mmap the events: %s\n",
>  			  str_error_r(errno, sbuf, sizeof(sbuf)));
>  		perf_evlist__close(evlist);
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index f4d9fc5..b3ef33f 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -300,7 +300,7 @@ static int record__mmap_evlist(struct record *rec,
>  	struct record_opts *opts = &rec->opts;
>  	char msg[512];
> 
> -	if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, false,
> +	if (perf_evlist__mmap_ex(evlist, opts->mmap_pages,
>  				 opts->auxtrace_mmap_pages,
>  				 opts->auxtrace_snapshot_mode) < 0) {
>  		if (errno == EPERM) {
> @@ -481,7 +481,7 @@ static int record__mmap_read_evlist(struct record
> *rec, struct perf_evlist *evli
>  		struct auxtrace_mmap *mm = &maps[i].auxtrace_mmap;
> 
>  		if (maps[i].base) {
> -			if (perf_mmap__push(&maps[i], evlist->overwrite,
> backward, rec, record__pushfn) != 0) {
> +			if (perf_mmap__push(&maps[i], backward, rec,
> record__pushfn) != 0) {
>  				rc = -1;
>  				goto out;
>  			}
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index 477a869..83d2ae2 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -902,7 +902,7 @@ static int perf_top__start_counters(struct perf_top
> *top)
>  		}
>  	}
> 
> -	if (perf_evlist__mmap(evlist, opts->mmap_pages, false) < 0) {
> +	if (perf_evlist__mmap(evlist, opts->mmap_pages) < 0) {
>  		ui__error("Failed to mmap with %d (%s)\n",
>  			    errno, str_error_r(errno, msg, sizeof(msg)));
>  		goto out_err;
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index c373f9a..c3f2f98 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -2404,7 +2404,7 @@ static int trace__run(struct trace *trace, int argc,
> const char **argv)
>  	if (err < 0)
>  		goto out_error_apply_filters;
> 
> -	err = perf_evlist__mmap(evlist, trace->opts.mmap_pages, false);
> +	err = perf_evlist__mmap(evlist, trace->opts.mmap_pages);
>  	if (err < 0)
>  		goto out_error_mmap;
> 
> diff --git a/tools/perf/tests/backward-ring-buffer.c
> b/tools/perf/tests/backward-ring-buffer.c
> index 992c917..bdebcf9 100644
> --- a/tools/perf/tests/backward-ring-buffer.c
> +++ b/tools/perf/tests/backward-ring-buffer.c
> @@ -58,7 +58,7 @@ static int do_test(struct perf_evlist *evlist, int
> mmap_pages,
>  	int err;
>  	char sbuf[STRERR_BUFSIZE];
> 
> -	err = perf_evlist__mmap(evlist, mmap_pages, false);
> +	err = perf_evlist__mmap(evlist, mmap_pages);
>  	if (err < 0) {
>  		pr_debug("perf_evlist__mmap: %s\n",
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
> index 34c22cd..c433dd3 100644
> --- a/tools/perf/tests/bpf.c
> +++ b/tools/perf/tests/bpf.c
> @@ -167,7 +167,7 @@ static int do_test(struct bpf_object *obj, int
> (*func)(void),
>  		goto out_delete_evlist;
>  	}
> 
> -	err = perf_evlist__mmap(evlist, opts.mmap_pages, false);
> +	err = perf_evlist__mmap(evlist, opts.mmap_pages);
>  	if (err < 0) {
>  		pr_debug("perf_evlist__mmap: %s\n",
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
> index 466a462..b6c813e 100644
> --- a/tools/perf/tests/code-reading.c
> +++ b/tools/perf/tests/code-reading.c
> @@ -638,7 +638,7 @@ static int do_test_code_reading(bool try_kcore)
>  		break;
>  	}
> 
> -	ret = perf_evlist__mmap(evlist, UINT_MAX, false);
> +	ret = perf_evlist__mmap(evlist, UINT_MAX);
>  	if (ret < 0) {
>  		pr_debug("perf_evlist__mmap failed\n");
>  		goto out_put;
> diff --git a/tools/perf/tests/keep-tracking.c b/tools/perf/tests/keep-tracking.c
> index 7394286..b282916 100644
> --- a/tools/perf/tests/keep-tracking.c
> +++ b/tools/perf/tests/keep-tracking.c
> @@ -94,7 +94,7 @@ int test__keep_tracking(struct test *test
> __maybe_unused, int subtest __maybe_un
>  		goto out_err;
>  	}
> 
> -	CHECK__(perf_evlist__mmap(evlist, UINT_MAX, false));
> +	CHECK__(perf_evlist__mmap(evlist, UINT_MAX));
> 
>  	/*
>  	 * First, test that a 'comm' event can be found when the event is
> diff --git a/tools/perf/tests/mmap-basic.c b/tools/perf/tests/mmap-basic.c
> index 667d696..f43d862 100644
> --- a/tools/perf/tests/mmap-basic.c
> +++ b/tools/perf/tests/mmap-basic.c
> @@ -93,7 +93,7 @@ int test__basic_mmap(struct test *test
> __maybe_unused, int subtest __maybe_unuse
>  		expected_nr_events[i] = 1 + rand() % 127;
>  	}
> 
> -	if (perf_evlist__mmap(evlist, 128, false) < 0) {
> +	if (perf_evlist__mmap(evlist, 128) < 0) {
>  		pr_debug("failed to mmap events: %d (%s)\n", errno,
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
>  		goto out_delete_evlist;
> diff --git a/tools/perf/tests/openat-syscall-tp-fields.c
> b/tools/perf/tests/openat-syscall-tp-fields.c
> index b6ee1c4..f68d818 100644
> --- a/tools/perf/tests/openat-syscall-tp-fields.c
> +++ b/tools/perf/tests/openat-syscall-tp-fields.c
> @@ -63,7 +63,7 @@ int test__syscall_openat_tp_fields(struct test *test
> __maybe_unused, int subtest
>  		goto out_delete_evlist;
>  	}
> 
> -	err = perf_evlist__mmap(evlist, UINT_MAX, false);
> +	err = perf_evlist__mmap(evlist, UINT_MAX);
>  	if (err < 0) {
>  		pr_debug("perf_evlist__mmap: %s\n",
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> diff --git a/tools/perf/tests/perf-record.c b/tools/perf/tests/perf-record.c
> index 19b6500..f9fbd8b 100644
> --- a/tools/perf/tests/perf-record.c
> +++ b/tools/perf/tests/perf-record.c
> @@ -140,7 +140,7 @@ int test__PERF_RECORD(struct test *test
> __maybe_unused, int subtest __maybe_unus
>  	 * fds in the same CPU to be injected in the same mmap ring buffer
>  	 * (using ioctl(PERF_EVENT_IOC_SET_OUTPUT)).
>  	 */
> -	err = perf_evlist__mmap(evlist, opts.mmap_pages, false);
> +	err = perf_evlist__mmap(evlist, opts.mmap_pages);
>  	if (err < 0) {
>  		pr_debug("perf_evlist__mmap: %s\n",
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c
> index c468e6c..fd01b24 100644
> --- a/tools/perf/tests/sw-clock.c
> +++ b/tools/perf/tests/sw-clock.c
> @@ -77,7 +77,7 @@ static int __test__sw_clock_freq(enum perf_sw_ids
> clock_id)
>  		goto out_delete_evlist;
>  	}
> 
> -	err = perf_evlist__mmap(evlist, 128, false);
> +	err = perf_evlist__mmap(evlist, 128);
>  	if (err < 0) {
>  		pr_debug("failed to mmap event: %d (%s)\n", errno,
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
> diff --git a/tools/perf/tests/switch-tracking.c b/tools/perf/tests/switch-
> tracking.c
> index 2acd785..9fee2a0 100644
> --- a/tools/perf/tests/switch-tracking.c
> +++ b/tools/perf/tests/switch-tracking.c
> @@ -448,7 +448,7 @@ int test__switch_tracking(struct test *test
> __maybe_unused, int subtest __maybe_
>  		goto out;
>  	}
> 
> -	err = perf_evlist__mmap(evlist, UINT_MAX, false);
> +	err = perf_evlist__mmap(evlist, UINT_MAX);
>  	if (err) {
>  		pr_debug("perf_evlist__mmap failed!\n");
>  		goto out_err;
> diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c
> index 4fb6609..4ba5a27 100644
> --- a/tools/perf/tests/task-exit.c
> +++ b/tools/perf/tests/task-exit.c
> @@ -96,7 +96,7 @@ int test__task_exit(struct test *test __maybe_unused,
> int subtest __maybe_unused
>  		goto out_delete_evlist;
>  	}
> 
> -	if (perf_evlist__mmap(evlist, 128, false) < 0) {
> +	if (perf_evlist__mmap(evlist, 128) < 0) {
>  		pr_debug("failed to mmap events: %d (%s)\n", errno,
>  			 str_error_r(errno, sbuf, sizeof(sbuf)));
>  		goto out_delete_evlist;
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 4c5daba..4948d3d 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -711,7 +711,7 @@ union perf_event
> *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int
>  	 * 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);
> +	return perf_mmap__read_forward(md, false);

If we remove the 'overwrite' in forward, I think 'check_messup' is useless. 
It's better to remove it as well.

>  }
> 
>  union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist
> *evlist, int idx)
> @@ -738,7 +738,7 @@ void perf_evlist__mmap_read_catchup(struct
> perf_evlist *evlist, int idx)
> 
>  void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
>  {
> -	perf_mmap__consume(&evlist->mmap[idx], evlist->overwrite);
> +	perf_mmap__consume(&evlist->mmap[idx], false);

I think we still need to remove 'overwrite' in the implementation of
perf_mmap__consume.


There are too many generic functions are changed in this patch.
I think it's better to split into several patches.
It's better to have one generic function changed in one patch.

Thanks,
Kan

>  }
> 
>  static void perf_evlist__munmap_nofree(struct perf_evlist *evlist)
> @@ -1058,14 +1058,14 @@ int perf_evlist__parse_mmap_pages(const
> struct option *opt, const char *str,
>   * Return: %0 on success, negative error code otherwise.
>   */
>  int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
> -			 bool overwrite, unsigned int auxtrace_pages,
> +			 unsigned int auxtrace_pages,
>  			 bool auxtrace_overwrite)
>  {
>  	struct perf_evsel *evsel;
>  	const struct cpu_map *cpus = evlist->cpus;
>  	const struct thread_map *threads = evlist->threads;
>  	struct mmap_params mp = {
> -		.prot = PROT_READ | (overwrite ? 0 : PROT_WRITE),
> +		.prot = PROT_READ | PROT_WRITE,
>  	};
> 
>  	if (!evlist->mmap)
> @@ -1076,7 +1076,6 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist,
> unsigned int pages,
>  	if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) <
> 0)
>  		return -ENOMEM;
> 
> -	evlist->overwrite = overwrite;
>  	evlist->mmap_len = perf_evlist__mmap_size(pages);
>  	pr_debug("mmap size %zuB\n", evlist->mmap_len);
>  	mp.mask = evlist->mmap_len - page_size - 1;
> @@ -1097,10 +1096,9 @@ int perf_evlist__mmap_ex(struct perf_evlist
> *evlist, unsigned int pages,
>  	return perf_evlist__mmap_per_cpu(evlist, &mp);
>  }
> 
> -int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
> -		      bool overwrite)
> +int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages)
>  {
> -	return perf_evlist__mmap_ex(evlist, pages, overwrite, 0, false);
> +	return perf_evlist__mmap_ex(evlist, pages, 0, false);
>  }
> 
>  int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target)
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index 8c433e9..1dd3291 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -30,7 +30,6 @@ struct perf_evlist {
>  	int		 nr_entries;
>  	int		 nr_groups;
>  	int		 nr_mmaps;
> -	bool		 overwrite;
>  	bool		 enabled;
>  	bool		 has_user_cpus;
>  	size_t		 mmap_len;
> @@ -168,10 +167,9 @@ int perf_evlist__parse_mmap_pages(const struct
> option *opt,
>  unsigned long perf_event_mlock_kb_in_pages(void);
> 
>  int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
> -			 bool overwrite, unsigned int auxtrace_pages,
> +			 unsigned int auxtrace_pages,
>  			 bool auxtrace_overwrite);
> -int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
> -		      bool overwrite);
> +int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages);
>  void perf_evlist__munmap(struct perf_evlist *evlist);
> 
>  size_t perf_evlist__mmap_size(unsigned long pages);
> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index 9fe5f9c..703ed41 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -299,7 +299,7 @@ static int rb_find_range(void *data, int mask, u64
> head, u64 old,
>  	return backward_rb_find_range(data, mask, head, start, end);
>  }
> 
> -int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool
> backward,
> +int perf_mmap__push(struct perf_mmap *md, bool backward,
>  		    void *to, int push(void *to, void *buf, size_t size))
>  {
>  	u64 head = perf_mmap__read_head(md);
> @@ -321,7 +321,7 @@ int perf_mmap__push(struct perf_mmap *md, bool
> overwrite, bool backward,
>  		WARN_ONCE(1, "failed to keep up with mmap data. (warn
> only once)\n");
> 
>  		md->prev = head;
> -		perf_mmap__consume(md, overwrite || backward);
> +		perf_mmap__consume(md, backward);
>  		return 0;
>  	}
> 
> @@ -346,7 +346,7 @@ int perf_mmap__push(struct perf_mmap *md, bool
> overwrite, bool backward,
>  	}
> 
>  	md->prev = head;
> -	perf_mmap__consume(md, overwrite || backward);
> +	perf_mmap__consume(md, backward);
>  out:
>  	return rc;
>  }
> diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
> index efd78b8..2c3d291 100644
> --- a/tools/perf/util/mmap.h
> +++ b/tools/perf/util/mmap.h
> @@ -89,7 +89,7 @@ static inline void perf_mmap__write_tail(struct
> perf_mmap *md, u64 tail)
>  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);
> 
> -int perf_mmap__push(struct perf_mmap *md, bool overwrite, bool
> backward,
> +int perf_mmap__push(struct perf_mmap *md, bool backward,
>  		    void *to, int push(void *to, void *buf, size_t size));
> 
>  size_t perf_mmap__mmap_len(struct perf_mmap *map);
> diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
> index c129e99..ece33b4 100644
> --- a/tools/perf/util/python.c
> +++ b/tools/perf/util/python.c
> @@ -856,14 +856,14 @@ static PyObject *pyrf_evlist__mmap(struct
> pyrf_evlist *pevlist,
>  				   PyObject *args, PyObject *kwargs)
>  {
>  	struct perf_evlist *evlist = &pevlist->evlist;
> -	static char *kwlist[] = { "pages", "overwrite", NULL };
> -	int pages = 128, overwrite = false;
> +	static char *kwlist[] = { "pages", NULL };
> +	int pages = 128;
> 
> -	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ii", kwlist,
> -					 &pages, &overwrite))
> +	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|i", kwlist,
> +					 &pages))
>  		return NULL;
> 
> -	if (perf_evlist__mmap(evlist, pages, overwrite) < 0) {
> +	if (perf_evlist__mmap(evlist, pages) < 0) {
>  		PyErr_SetFromErrno(PyExc_OSError);
>  		return NULL;
>  	}
> --
> 2.10.1

[PATCH 7/7] perf tools: Remove prot field in mmap param

[Wang Nan]

After removing the concept of 'overwrite' in code level, now the
prot is determinated by write_backward. There's no need to pass
prot from perf_evlist__mmap_ex().

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/util/evlist.c | 17 ++++++-----------
 tools/perf/util/mmap.c   |  4 ++--
 tools/perf/util/mmap.h   |  4 ++--
 3 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 4948d3d..0d713e0 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -799,28 +799,23 @@ perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
 }
 
 static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
-				       struct mmap_params *_mp, int cpu_idx,
+				       struct mmap_params *mp, int cpu_idx,
 				       int thread, int *_output, int *_output_backward)
 {
 	struct perf_evsel *evsel;
 	int revent;
 	int evlist_cpu = cpu_map__cpu(evlist->cpus, cpu_idx);
-	struct mmap_params *mp;
 
 	evlist__for_each_entry(evlist, evsel) {
 		struct perf_mmap *maps = evlist->mmap;
-		struct mmap_params rdonly_mp;
 		int *output = _output;
 		int fd;
 		int cpu;
+		int prot = PROT_READ;
 
-		mp = _mp;
 		if (evsel->attr.write_backward) {
 			output = _output_backward;
 			maps = evlist->backward_mmap;
-			rdonly_mp = *_mp;
-			rdonly_mp.prot &= ~PROT_WRITE;
-			mp = &rdonly_mp;
 
 			if (!maps) {
 				maps = perf_evlist__alloc_mmap(evlist);
@@ -830,6 +825,8 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 				if (evlist->bkw_mmap_state == BKW_MMAP_NOTREADY)
 					perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING);
 			}
+		} else {
+			prot |= PROT_WRITE;
 		}
 
 		if (evsel->system_wide && thread)
@@ -844,7 +841,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 		if (*output == -1) {
 			*output = fd;
 
-			if (perf_mmap__mmap(&maps[idx], mp, *output)  < 0)
+			if (perf_mmap__mmap(&maps[idx], mp, prot, *output)  < 0)
 				return -1;
 		} else {
 			if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0)
@@ -1064,9 +1061,7 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 	struct perf_evsel *evsel;
 	const struct cpu_map *cpus = evlist->cpus;
 	const struct thread_map *threads = evlist->threads;
-	struct mmap_params mp = {
-		.prot = PROT_READ | PROT_WRITE,
-	};
+	struct mmap_params mp;
 
 	if (!evlist->mmap)
 		evlist->mmap = perf_evlist__alloc_mmap(evlist);
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 703ed41..40e91a0 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -219,7 +219,7 @@ void perf_mmap__munmap(struct perf_mmap *map)
 	auxtrace_mmap__munmap(&map->auxtrace_mmap);
 }
 
-int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
+int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int prot, int fd)
 {
 	/*
 	 * The last one will be done at perf_evlist__mmap_consume(), so that we
@@ -237,7 +237,7 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
 	refcount_set(&map->refcnt, 2);
 	map->prev = 0;
 	map->mask = mp->mask;
-	map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
+	map->base = mmap(NULL, perf_mmap__mmap_len(map), prot,
 			 MAP_SHARED, fd, 0);
 	if (map->base == MAP_FAILED) {
 		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index 2c3d291..1f6fcc6 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -53,11 +53,11 @@ enum bkw_mmap_state {
 };
 
 struct mmap_params {
-	int			    prot, mask;
+	int			    mask;
 	struct auxtrace_mmap_params auxtrace_mp;
 };
 
-int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd);
+int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int prot, int fd);
 void perf_mmap__munmap(struct perf_mmap *map);
 
 void perf_mmap__get(struct perf_mmap *map);
-- 
2.10.1

Re: [PATCH 7/7] perf tools: Remove prot field in mmap param

[Jiri Olsa]

On Mon, Nov 13, 2017 at 01:38:09AM +0000, Wang Nan wrote:
> After removing the concept of 'overwrite' in code level, now the
> prot is determinated by write_backward. There's no need to pass
> prot from perf_evlist__mmap_ex().
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/util/evlist.c | 17 ++++++-----------
>  tools/perf/util/mmap.c   |  4 ++--
>  tools/perf/util/mmap.h   |  4 ++--
>  3 files changed, 10 insertions(+), 15 deletions(-)
> 
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 4948d3d..0d713e0 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -799,28 +799,23 @@ perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
>  }
>  
>  static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
> -				       struct mmap_params *_mp, int cpu_idx,
> +				       struct mmap_params *mp, int cpu_idx,
>  				       int thread, int *_output, int *_output_backward)
>  {
>  	struct perf_evsel *evsel;
>  	int revent;
>  	int evlist_cpu = cpu_map__cpu(evlist->cpus, cpu_idx);
> -	struct mmap_params *mp;
>  
>  	evlist__for_each_entry(evlist, evsel) {
>  		struct perf_mmap *maps = evlist->mmap;
> -		struct mmap_params rdonly_mp;
>  		int *output = _output;
>  		int fd;
>  		int cpu;
> +		int prot = PROT_READ;

can't you set the PROT_READ in struct mmap_params *mp as its default value?

		mp->prot = PROT_READ;

>  
> -		mp = _mp;
>  		if (evsel->attr.write_backward) {
>  			output = _output_backward;
>  			maps = evlist->backward_mmap;
> -			rdonly_mp = *_mp;
> -			rdonly_mp.prot &= ~PROT_WRITE;
> -			mp = &rdonly_mp;
>  
>  			if (!maps) {
>  				maps = perf_evlist__alloc_mmap(evlist);
> @@ -830,6 +825,8 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
>  				if (evlist->bkw_mmap_state == BKW_MMAP_NOTREADY)
>  					perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING);
>  			}
> +		} else {
> +			prot |= PROT_WRITE;
>  		}
>  
>  		if (evsel->system_wide && thread)
> @@ -844,7 +841,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
>  		if (*output == -1) {
>  			*output = fd;
>  
> -			if (perf_mmap__mmap(&maps[idx], mp, *output)  < 0)
> +			if (perf_mmap__mmap(&maps[idx], mp, prot, *output)  < 0)

so there's no need for the extra 'prot' param in here

jirka

Re: [PATCH 7/7] perf tools: Remove prot field in mmap param

[Jiri Olsa]

On Mon, Nov 13, 2017 at 01:38:09AM +0000, Wang Nan wrote:
> After removing the concept of 'overwrite' in code level, now the
> prot is determinated by write_backward. There's no need to pass
> prot from perf_evlist__mmap_ex().
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> ---
>  tools/perf/util/evlist.c | 17 ++++++-----------
>  tools/perf/util/mmap.c   |  4 ++--
>  tools/perf/util/mmap.h   |  4 ++--
>  3 files changed, 10 insertions(+), 15 deletions(-)
> 
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 4948d3d..0d713e0 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -799,28 +799,23 @@ perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
>  }
>  
>  static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
> -				       struct mmap_params *_mp, int cpu_idx,
> +				       struct mmap_params *mp, int cpu_idx,
>  				       int thread, int *_output, int *_output_backward)
>  {
>  	struct perf_evsel *evsel;
>  	int revent;
>  	int evlist_cpu = cpu_map__cpu(evlist->cpus, cpu_idx);
> -	struct mmap_params *mp;
>  
>  	evlist__for_each_entry(evlist, evsel) {
>  		struct perf_mmap *maps = evlist->mmap;
> -		struct mmap_params rdonly_mp;
>  		int *output = _output;
>  		int fd;
>  		int cpu;
> +		int prot = PROT_READ;
>  
> -		mp = _mp;
>  		if (evsel->attr.write_backward) {
>  			output = _output_backward;
>  			maps = evlist->backward_mmap;
> -			rdonly_mp = *_mp;
> -			rdonly_mp.prot &= ~PROT_WRITE;
> -			mp = &rdonly_mp;

I dont think we need the first patch, you're reverting it in here

jirka

RE: [PATCH 0/7] perf tools: Clarify overwrite and backward, bugfix

[Liang, Kan]

> Based on previous discussion, perf needs to support only two types
> of ringbuffer: read-write + forward, readonly + backward. This patchset
> completly removes the concept of 'overwrite' from code level, controls
> mapping permission using write_backward instead.

I think I suggested to remove the concept of backward/forward, keep
the overwrite. That's from user's perspective.
Here you use read-write + forward and readonly + backward, which
should be from kernel 's perspective. It's OK for me either.
However, we should make the concepts connected by clearly documented,
not just in changelog.

I suggest you may create a new file, ringbuffer.txt, in Documentation to
explain, the types of ringbuffer, how do they work, what's connections
between overwrite and readonly + backward, and so on. 


> 
> Wang Nan (7):
>   perf mmap: Fix perf backward recording
>   perf tests: Set evlist of test__backward_ring_buffer() to !overwrite
>   perf tests: Set evlist of test__sw_clock_freq() to !overwrite
>   perf tests: Set evlist of test__basic_mmap() to !overwrite
>   perf tests: Set evlist of test__task_exit() to !overwrite
>   perf tools: Remove 'overwrite' concept from code level
>   perf tools: Remove prot field in mmap param
> 

You had another related fix "perf tool: Don't discard prev in backward
mode" https://lkml.org/lkml/2017/10/12/408
It has not been merged yet. It needs to backport.
I think you may want to add it in this series as well.


Thanks,
Kan

>  tools/perf/arch/x86/tests/perf-time-to-tsc.c |  2 +-
>  tools/perf/builtin-kvm.c                     |  2 +-
>  tools/perf/builtin-record.c                  |  4 ++--
>  tools/perf/builtin-top.c                     |  2 +-
>  tools/perf/builtin-trace.c                   |  2 +-
>  tools/perf/tests/backward-ring-buffer.c      |  2 +-
>  tools/perf/tests/bpf.c                       |  2 +-
>  tools/perf/tests/code-reading.c              |  2 +-
>  tools/perf/tests/keep-tracking.c             |  2 +-
>  tools/perf/tests/mmap-basic.c                |  2 +-
>  tools/perf/tests/openat-syscall-tp-fields.c  |  2 +-
>  tools/perf/tests/perf-record.c               |  2 +-
>  tools/perf/tests/sw-clock.c                  |  2 +-
>  tools/perf/tests/switch-tracking.c           |  2 +-
>  tools/perf/tests/task-exit.c                 |  2 +-
>  tools/perf/util/evlist.c                     | 21 ++++++++++-----------
>  tools/perf/util/evlist.h                     |  6 ++----
>  tools/perf/util/mmap.c                       | 10 +++++-----
>  tools/perf/util/mmap.h                       |  6 +++---
>  tools/perf/util/python.c                     | 10 +++++-----
>  20 files changed, 41 insertions(+), 44 deletions(-)
> 
> --
> 2.10.1