perf, tools: Refactor and support interval and CSV metrics

From: Andi Kleen
Date: Fri Feb 26 2016 - 19:28:55 EST

[v5: Fix mainly bisect problems. No regressions introduced by one
patch and fixed again later. Some minor fixes in addition]
[v6: Fix running/noise printing patch.]
[v7: Reorder and merge two patches to avoid a bisect hole where unsupported was
printed as 0]
[v8: Minor fixes for review feedback. See changelog in patches.]
[v9: Fix newline bug. Add support for -A for --metric-only]
[v10: Remove extra "noise" printing (Jiri)
Fix fields in documentation (Jiri)]
[v11: Fix manpage again. Avoid extra metric output in CSV mode.]
[v12: Move CSV metrics fields to after running/enabled/variance.
Minor fixes.]
[v13: Address review comments. Now probe for stalled events
in advance to avoid empty columns or lines. Fix -A shadowing.
Various minor changes. Drop merged patches.]

Currently perf stat does not support printing computed metrics for interval (-I xxx)
or CSV (-x,) mode. For example IPC or TSX metrics over time are quite useful to know.

This patch implements them. The main obstacle was that the
metrics printing was all open coded all over the metrics computation code.
The second patch refactors the metrics printing to work through call backs that
can be more easily changed. This also cleans up the metrics printing significantly.
The indentation is now handled through printf, no more need to manually count spaces.

Then based on that it implements metrics printing for CSV and interval mode,
and finally a --metric-only mode.

Example output:

% perf stat -I1000 -a sleep 1
# time counts unit events metric multiplex
1.001301370 12020.049593 task-clock (msec) (100.00%)
1.001301370 3,952 context-switches # 0.329 K/sec (100.00%)
1.001301370 69 cpu-migrations # 0.006 K/sec (100.00%)
1.001301370 76 page-faults # 0.006 K/sec
1.001301370 386,582,789 cycles # 0.032 GHz (100.00%)
1.001301370 716,441,544 stalled-cycles-frontend # 185.33% frontend cycles idle (100.00%)
1.001301370 <not supported> stalled-cycles-backend
1.001301370 101,751,678 instructions # 0.26 insn per cycle
1.001301370 # 7.04 stalled cycles per insn (100.00%)
1.001301370 20,914,692 branches # 1.740 M/sec (100.00%)
1.001301370 1,943,630 branch-misses # 9.29% of all branches

CSV mode:

% perf stat -x, -I1000 -a sleep 1
1.000982778,6971803638,,stalled-cycles-frontend,12006902870,100.00,361.18,frontend cycles idle
1.000982778,464493941,,instructions,12006873327,100.00,0.24,insn per cycle
1.000982778,,,,,,15.01,stalled cycles per insn
1.000982778,4933638,,branch-misses,12006648104,100.00,5.70,of all branches

Now includes metrics

Metric only mode:

Concicse information if you only care about computed metrics, not raw values

% perf stat --metric-only -a -I 1000
1.001452803 frontend cycles idle insn per cycle stalled cycles per insn branch-misses of all branches
1.001452803 158.91% 0.66 2.39 2.92%
2.002192321 180.63% 0.76 2.08 2.96%
3.003088282 150.59% 0.62 2.57 2.84%
4.004369835 196.20% 0.98 1.62 3.79%
5.005227314 231.98% 0.84 1.90 4.71%

Metric only mode in CSV (flat format, easy to plot and analyze in statistical tools like JMP, R, pandas, gnuplot):

% perf stat -x, --metric-only -a -I 1000
1.001381652,frontend cycles idle,insn per cycle,stalled cycles per insn,branch-misses of all branches,

Available in
git:// perf/stat-metrics-17