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+##############################################################################
+# Copyright (c) 2016 CENGN and others.
+#
+# All rights reserved. This program and the accompanying materials
+# are made available under the terms of the Apache License, Version 2.0
+# which accompanies this distribution, and is available at
+# http://www.apache.org/licenses/LICENSE-2.0
+##############################################################################
+from storperf.utilities import data_treatment as DataTreatment
+from storperf.utilities import math as math
+
+
+def steady_state(data_series):
+ """
+ This function seeks to detect steady state given on a measurement
+ window given the data series of that measurement window following
+ the pattern : [[x1,y1], [x2,y2], ..., [xm,ym]]. m represents the number
+ of points recorded in the measurement window, x which represents the
+ time, and y which represents the Volume performance variable being
+ tested e.g. IOPS, latency...
+ The function returns a boolean describing wether or not steady state
+ has been reached with the data that is passed to it.
+ """
+
+ # Pre conditioning the data to match the algorithms
+ treated_data = DataTreatment.data_treatment(data_series)
+
+ # Calculating useful values invoking dedicated functions
+ slope_value = math.slope(treated_data['slope_data'])
+ range_value = math.range_value(treated_data['range_data'])
+ average_value = math.average(treated_data['average_data'])
+
+ if (slope_value is not None and range_value is not None and
+ average_value is not None):
+ # Verification of the Steady State conditions following the SNIA
+ # definition
+ range_condition = range_value < 0.20 * abs(average_value)
+ slope_condition = slope_value < 0.10 * abs(average_value)
+
+ steady_state = range_condition and slope_condition
+
+ else:
+ steady_state = False
+
+ return steady_state