[PATCH v5 0/8] perf tools: Support overwritable ring buffer

From: Wang Nan
Date: Wed May 25 2016 - 01:05:44 EST

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

# 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.

Wang Nan (8):
perf tools: Check 'base' pointer before checking refcnt when put a
perf tools: Choose correct reading direction according to
perf tests: Add testcase for auxiliary evlist
perf record: Introduce rec->overwrite_evlist for overwritable events
perf record: Toggle overwrite ring buffer for reading
perf tools: Enable overwrite settings
perf tools: Don't warn about out of order event if write_backward is
perf tools: Check write_backward during evlist config

tools/perf/Documentation/perf-record.txt | 14 ++
tools/perf/builtin-record.c | 285 +++++++++++++++++++++++++++----
tools/perf/perf.h | 1 +
tools/perf/tests/backward-ring-buffer.c | 86 +++++++---
tools/perf/util/evlist.c | 15 +-
tools/perf/util/evlist.h | 2 +
tools/perf/util/evsel.c | 27 +--
tools/perf/util/evsel.h | 15 ++
tools/perf/util/parse-events.c | 20 ++-
tools/perf/util/parse-events.h | 2 +
tools/perf/util/parse-events.l | 2 +
tools/perf/util/record.c | 17 ++
tools/perf/util/session.c | 22 ++-
13 files changed, 435 insertions(+), 73 deletions(-)

Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx