From: Wang Nan <wangnan0@huawei.com>
To: <linux-kernel@vger.kernel.org>, <kan.liang@intel.com>,
<acme@kernel.org>, <jolsa@redhat.com>, <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Subject: [PATCH 1/2] perf mmap: Fix perf backward recording
Date: Wed, 1 Nov 2017 05:53:26 +0000 [thread overview]
Message-ID: <20171101055327.141281-2-wangnan0@huawei.com> (raw)
In-Reply-To: <20171101055327.141281-1-wangnan0@huawei.com>
perf record backward recording doesn't work as we expected: it never
overwrite when ring buffer full.
Test:
(Run a busy printing python 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
next prev parent reply other threads:[~2017-11-01 5:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-01 5:53 [PATCH 0/2] perf record: Fix --overwrite and clarify concepts Wang Nan
2017-11-01 5:53 ` Wang Nan [this message]
2017-11-01 9:49 ` [PATCH 1/2] perf mmap: Fix perf backward recording Namhyung Kim
2017-11-01 10:32 ` Wangnan (F)
2017-11-01 12:00 ` Namhyung Kim
2017-11-01 12:10 ` Wangnan (F)
2017-11-01 12:39 ` Jiri Olsa
2017-11-01 12:56 ` Wangnan (F)
2017-11-02 15:12 ` Jiri Olsa
2017-11-01 13:57 ` Liang, Kan
2017-11-01 16:12 ` Wangnan (F)
2017-11-01 16:22 ` Liang, Kan
2017-11-02 5:34 ` Namhyung Kim
2017-11-02 13:25 ` Liang, Kan
2017-11-02 14:59 ` Jiri Olsa
2017-11-01 5:53 ` [PATCH 2/2] perf record: Replace 'overwrite' by 'flightrecorder' for better naming Wang Nan
2017-11-01 10:03 ` Namhyung Kim
2017-11-01 10:17 ` Wangnan (F)
2017-11-01 12:03 ` Namhyung Kim
2017-11-01 13:26 ` Liang, Kan
2017-11-01 14:05 ` Wangnan (F)
2017-11-01 14:22 ` Liang, Kan
2017-11-01 14:44 ` Wangnan (F)
2017-11-01 15:04 ` Liang, Kan
2017-11-01 16:00 ` Wangnan (F)
2017-11-01 16:13 ` Liang, Kan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171101055327.141281-2-wangnan0@huawei.com \
--to=wangnan0@huawei.com \
--cc=acme@kernel.org \
--cc=jolsa@redhat.com \
--cc=kan.liang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=namhyung@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®