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| author | Juri Lelli <juri.lelli@gmail.com> | 2013-06-12 10:03:18 (GMT) |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-06-20 03:32:09 (GMT) |
| commit | 52d85d763086594f139bf7d3a5641abeb91d9f57 (patch) | |
| tree | ef1e85c2ac60076ecc3a31a60391653acff97e0b /tools | |
| parent | 195a84d91e92ee3fe571a2086a6db7e17bf5bc7c (diff) | |
| download | linux-52d85d763086594f139bf7d3a5641abeb91d9f57.tar.xz | |
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')
0 files changed, 0 insertions, 0 deletions