util: Add script to plot DRAM low power sweep

This change adds a script to generate graphs from the stats file
output by the configuration script low_power_sweep.py.

The graphs show stacked bars for time spent and energy consumed
wherein each component of the stacked bar represents a DRAM power
state (Idle, Refresh, Active, Active Power-down, Precharge Power-down
and Self-refresh). The script generates one plot per delay value. It
also generates a pdf (--pdf option) in which the graphs are laid out
such that you can easily compare how the increasing delay and other
swept params affect the resulting energy.

Change-Id: Id80b0947bfde27e11e5505b23a3adb30f793a43f
Reviewed-by: Wendy Elsasser <wendy.elsasser@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5727
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

util/plot_dram/dram_lat_mem_rd_plot.py

@@ -0,0 +1,151 @@
+#!/usr/bin/env python2
+
+# Copyright (c) 2015 ARM Limited
+# All rights reserved
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met: redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer;
+# redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Hansson
+
+try:
+    import matplotlib.pyplot as plt
+    import matplotlib as mpl
+    import numpy as np
+except ImportError:
+    print "Failed to import matplotlib and numpy"
+    exit(-1)
+
+import sys
+import re
+
+# This script is intended to post process and plot the output from
+# running configs/dram/lat_mem_rd.py, as such it parses the simout and
+# stats.txt to get the relevant data points.
+def main():
+
+    if len(sys.argv) != 2:
+        print "Usage: ", sys.argv[0], "<simout directory>"
+        exit(-1)
+
+    try:
+        stats = open(sys.argv[1] + '/stats.txt', 'r')
+    except IOError:
+        print "Failed to open ", sys.argv[1] + '/stats.txt', " for reading"
+        exit(-1)
+
+    try:
+        simout = open(sys.argv[1] + '/simout', 'r')
+    except IOError:
+        print "Failed to open ", sys.argv[1] + '/simout', " for reading"
+        exit(-1)
+
+    # Get the address ranges
+    got_ranges = False
+    ranges = []
+
+    iterations = 1
+
+    for line in simout:
+        if got_ranges:
+            ranges.append(int(line) / 1024)
+
+        match = re.match("lat_mem_rd with (\d+) iterations, ranges:.*", line)
+        if match:
+            got_ranges = True
+            iterations = int(match.groups(0)[0])
+
+    simout.close()
+
+    if not got_ranges:
+        print "Failed to get address ranges, ensure simout is up-to-date"
+        exit(-1)
+
+    # Now parse the stats
+    raw_rd_lat = []
+
+    for line in stats:
+        match = re.match(".*readLatencyHist::mean\s+(.+)\s+#.*", line)
+        if match:
+            raw_rd_lat.append(float(match.groups(0)[0]) / 1000)
+    stats.close()
+
+    # The stats also contain the warming, so filter the latency stats
+    i = 0
+    filtered_rd_lat = []
+    for l in raw_rd_lat:
+        if i % (iterations + 1) == 0:
+            pass
+        else:
+            filtered_rd_lat.append(l)
+        i = i + 1
+
+    # Next we need to take care of the iterations
+    rd_lat = []
+    for i in range(iterations):
+        rd_lat.append(filtered_rd_lat[i::iterations])
+
+    final_rd_lat = map(lambda p: min(p), zip(*rd_lat))
+
+    # Sanity check
+    if not (len(ranges) == len(final_rd_lat)):
+        print "Address ranges (%d) and read latency (%d) do not match" % \
+            (len(ranges), len(final_rd_lat))
+        exit(-1)
+
+    for (r, l) in zip(ranges, final_rd_lat):
+        print r, round(l, 2)
+
+    # lazy version to check if an integer is a power of two
+    def is_pow2(num):
+        return num != 0 and ((num & (num - 1)) == 0)
+
+    plt.semilogx(ranges, final_rd_lat)
+
+    # create human readable labels
+    xticks_locations = [r for r in ranges if is_pow2(r)]
+    xticks_labels = []
+    for x in xticks_locations:
+        if x < 1024:
+            xticks_labels.append('%d kB' % x)
+        else:
+            xticks_labels.append('%d MB' % (x / 1024))
+    plt.xticks(xticks_locations, xticks_labels, rotation=-45)
+
+    plt.minorticks_off()
+    plt.xlim((xticks_locations[0], xticks_locations[-1]))
+    plt.ylabel("Latency (ns)")
+    plt.grid(True)
+    plt.show()
+
+if __name__ == "__main__":
+    main()