Peter Zijlstra 506d4bc8d5 perf stat: Change noise calculation to use stddev ... The current noise computation does: \Sum abs(n_i - avg(n)) * N^-1.5 Which is (afaik) not a regular noise function, and needs the complete sample set available to post-process. Change this to use a regular stddev computation which can be done by keeping a two sums: stddev = sqrt( 1/N (\Sum n_i^2) - avg(n)^2 ) For which we only need to keep \Sum n_i and \Sum n_i^2. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: <stable@kernel.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2009-09-04 16:33:07 +02:00
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perf	perf stat: Change noise calculation to use stddev	2009-09-04 16:33:07 +02:00