path: root/tools/perf/Documentation
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authorAndi Kleen <>2016-03-03 15:57:36 -0800
committerArnaldo Carvalho de Melo <>2016-03-10 16:49:40 -0300
commit54b5091606c18f68a7fc8b4ab03ac4592c7d2922 (patch)
treea6bb0f667c144e5b77efc72244f6ff93c6716283 /tools/perf/Documentation
parent6b45f7b2a37b0e00693985fd0abfc8e0319f91ce (diff)
perf stat: Implement --metric-only mode
Add a new mode to only print metrics. Sometimes we don't care about the raw values, just want the computed metrics. This allows more compact printing, so with -I each sample is only a single line. This also allows easier plotting and processing with other tools. The main target is with using --topdown, but it also works with -T and standard perf stat. A few metrics are not supported. To avoiding having to hardcode all the metrics in the code it uses a two pass approach: first compute dummy metrics and only print the headers in the print_metric callback. Then use the callback to print the actual values. There are some additional changes in the stat printout code to handle all metrics being on a single line. One issue is that the column code doesn't know in advance what events are not supported by the CPU, and it would be hard to find out as this could change based on dynamic conditions. That causes empty columns in some cases. The output can be fairly wide, often you may need more than 80 columns. Example: % perf stat -a -I 1000 --metric-only 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% v2: Lots of updates. v3: Use slightly narrower columns v4: Add comment Signed-off-by: Andi Kleen <> Acked-by: Jiri Olsa <> Link: Signed-off-by: Arnaldo Carvalho de Melo <>
Diffstat (limited to 'tools/perf/Documentation')
1 files changed, 4 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 8812d7319edb..82f0951754dd 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -147,6 +147,10 @@ Print count deltas every N milliseconds (minimum: 10ms)
The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution.
example: 'perf stat -I 1000 -e cycles -a sleep 5'
+Only print computed metrics. Print them in a single line.
+Don't show any raw values. Not supported with -A or --per-thread.
Aggregate counts per processor socket for system-wide mode measurements. This
is a useful mode to detect imbalance between sockets. To enable this mode,