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| author |   Juri Lelli <juri.lelli@gmail.com> | 2013-06-12 12:03:18 +0200 |
|---|---|---|
| committer |   Steven Rostedt <rostedt@goodmis.org> | 2013-06-19 23:32:09 -0400 |
| commit | 52d85d763086594f139bf7d3a5641abeb91d9f57 (patch) | |
| tree | ef1e85c2ac60076ecc3a31a60391653acff97e0b /tools/perf/scripts/python/export-to-postgresql.py | |
| parent | tracing/kprobes: Remove unnecessary checking of trace_probe_is_enabled (diff) | |
| download | linux-dev-52d85d763086594f139bf7d3a5641abeb91d9f57.tar.xz linux-dev-52d85d763086594f139bf7d3a5641abeb91d9f57.zip | |
ftrace: Fix stddev calculation in function profiler
When FUNCTION_GRAPH_TRACER is enabled, ftrace can profile kernel functions
and print basic statistics about them. Unfortunately, running stddev
calculation is wrong. This patch corrects it implementing Welford’s method:
s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2) .
Link: http://lkml.kernel.org/r/1371031398-24048-1-git-send-email-juri.lelli@gmail.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'tools/perf/scripts/python/export-to-postgresql.py')
0 files changed, 0 insertions, 0 deletions