[PATCH v7 0/8] perf tools: Support overwritable ring buffer

From: Wang Nan
Date: Tue Jun 14 2016 - 22:24:01 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
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.

Wang Nan (8):
perf evlist: Introduce aux evlist
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
used
perf tools: Check write_backward during evlist config
perf record: Unmap overwrite evlist when event terminate

tools/perf/Documentation/perf-record.txt | 14 ++
tools/perf/builtin-record.c | 301 +++++++++++++++++++++++++++----
tools/perf/perf.h | 1 +
tools/perf/tests/backward-ring-buffer.c | 86 +++++++--
tools/perf/util/evlist.c | 34 ++--
tools/perf/util/evlist.h | 5 +-
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, 463 insertions(+), 83 deletions(-)

--
1.8.3.4