[PATCH v15 0/8] perf tools: Support overwritable ring buffer

From: Wang Nan
Date: Mon Jul 11 2016 - 02:55:09 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.

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

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.

v14 -> v15: Follow Jiri Olsa's suggestion: Improve test case; small code

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

Wang Nan (7):
perf evlist: Introduce aux evlist
perf tests: Add testcase for auxiliary evlist
perf record: Introduce rec->overwrite_evlist for overwritable events
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
perf tools: Add --tail-synthesize option

tools/perf/Documentation/perf-record.txt | 22 +++
tools/perf/builtin-record.c | 244 +++++++++++++++++++++++++++++--
tools/perf/perf.h | 2 +
tools/perf/tests/backward-ring-buffer.c | 102 ++++++++++---
tools/perf/util/evlist.c | 53 +++++--
tools/perf/util/evlist.h | 12 ++
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 ++-
12 files changed, 444 insertions(+), 56 deletions(-)