crunch_mpiGraph

#!/usr/bin/perl -w

# Copyright (c) 2007, Lawrence Livermore National Security (LLNS), LLC
# Produced at the Lawrence Livermore National Laboratory (LLNL)
# Written by Adam Moody <moody20@llnl.gov>.
# UCRL-CODE-232117.
# All rights reserved.
# 
# This file is part of mpiGraph. For details, see
#   http://www.sourceforge.net/projects/mpigraph
# Please also read the Additional BSD Notice below.
# 
# 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 disclaimer below.
# * Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the disclaimer (as noted below) in the documentation
#    and/or other materials provided with the distribution.
# * Neither the name of the LLNL 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 LLNL, THE U.S. DEPARTMENT
# OF ENERGY 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.
# 
# Additional BSD Notice
# 1. This notice is required to be provided under our contract with the U.S. Department
#    of Energy (DOE). This work was produced at LLNL under Contract No. W-7405-ENG-48
#    with the DOE.
# 2. Neither the United States Government nor LLNL nor any of their employees, makes
#    any warranty, express or implied, or assumes any liability or responsibility for
#    the accuracy, completeness, or usefulness of any information, apparatus, product,
#    or process disclosed, or represents that its use would not infringe privately-owned
#    rights.
# 3. Also, reference herein to any specific commercial products, process, or services
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#    or imply its endorsement, recommendation, or favoring by the United States Government
#    or LLNL. The views and opinions of authors expressed herein do not necessarily state
#    or reflect those of the United States Government or  LLNL and shall not be used for
#    advertising or product endorsement purposes.

# mpiGraph.c ========================================================================
#
# The crunch_mpiGraph script is then run on this output to generate a report.  A key
# component in this report are a pair of bitmap images representing bandwidth values
# between different task pairings.  Pixels in this image are colored depending on
# relative bandwidth values.  The maximum bandwidth value is set to pure white (value
# 255) and other values are scaled to black (0) depending on their percentage of the
# maximum.  Interesting patterns, or the lack thereof, make it easy to visually inspect
# and identify anomalous behavior in the system.  One may then zoom in and inspect
# image features in more detail by hovering the mouse cursor over the feature.
# Javascript embedded in the HTML report manages a pop-up tooltip with a zoomed-in
# view of the cursor location.

use FindBin;
use lib "$FindBin::Bin/.";
use hostlist_lite qw(compress);

# print usage then exit
sub usage
{
  my $exit_code = shift @_;
  print "\n";
  print "  crunch_mpiGraph -- process mpiGraph output into images or sort links by performance\n";
  print "\n";
  print "  Usage:  crunch_mpiGraph [-z|-nz] [-dist] <mpiGraph_output>\n";
  print "\n";
  print "  Node-to-node bandwidth options:\n";
  print "    -max       Set maximum bandwidth value (in MB/sec) to scale by\n";
  print "    -z         add javascript to html for zooming\n";
  print "               This may produce very large index.html files, but it's very useful for inspecting detailed features\n";
  print "    -nz        Disable javascript zoom in report\n";
  print "    -dist      set horizontal index to distance away from node in a given row, rather than MPI rank, so that\n";
  print "               data taken on different nodes at the same time are aligned into columns\n";
  print "\n";
  exit $exit_code;
}

# print usage if no arguments given on command line
if (not @ARGV) { usage(1); }

my @imagerows = ();

# set up default parameters and read command line arguments
$mode = "html";
$strip_mpi_rank = 1;
$maxbw = 0;
my %args = (
  dist => 0,
  zoom => 1,
);
while (@ARGV) {
  $arg = shift @ARGV;
  if ($arg =~ /^-/) {
    if    ($arg =~ /^-max/)     { $maxbw = shift @ARGV; }
    elsif ($arg =~ /^-html/)    { $mode = "html"; }
    elsif ($arg =~ /^-dist/)    { $args{dist} = 1; }
    elsif ($arg =~ /^-mpirank/) { $strip_mpi_rank = 0; }
    elsif ($arg =~ /^-z/)       { $args{zoom} = 1; }
    elsif ($arg =~ /^-nz/)      { $args{zoom} = 0; }
    else { print "Unrecognized option: $arg\n";  usage(1); } 
  } else {
    push @{$args{files}}, $arg;
  }
}

# compute_percentages($base, @values)
sub compute_percentages
{
  my $base = shift @_;
  my @ret  = ();
  foreach my $val (@_) {
    push @ret, sprintf("%3.1f%", $val / $base * 100);
  }
  return @ret;
}

# read in the mpiGraph files, values are averaged if there is more than one file
my %sendtable = ();
my %recvtable = ();
foreach my $file (@{$args{files}}) {
  if (not -r $file) { print "File unreadable: $file\n"; exit 0; }
  ($msgsize, $times, $window, $testuser, $testtime) = read_file($file, \%sendtable, \%recvtable);
}
my @sendstats = min_max_avg(\%sendtable);
my @recvstats = min_max_avg(\%recvtable);
my @sendpercs = compute_percentages($sendstats[1], @sendstats);
my @recvpercs = compute_percentages($recvstats[1], @recvstats);

####################
# NODE-TO-NODE BANDWIDTH REPORT
# Given a mpiGraph output, generate report including bandwidth images.
####################

if ($mode eq "html") {
  # generate html report
  $dir = (@{$args{files}})[0] . "_html";
  mkdir $dir;

  # write out send bitmap
  output_table_bitmap(\%sendtable, "$dir/send.bmp", @sendstats);
  my $sendimgjs = "var sendimgjs = [\n" . join(",\n", @imagerows) . "\n];\n";

  # write out recv bitmap
  output_table_bitmap(\%recvtable, "$dir/recv.bmp", @recvstats);
  my $recvimgjs = "var recvimgjs = [\n" . join(",\n", @imagerows) . "\n];\n";

  # write out index.html
  print "Writing $dir/index.html ...\n";
  open(HTML, ">$dir/index.html");
  print HTML "<html>\n";

  # write javascript
  print HTML "<script type=\"text/javascript\">";
  $zoomjs = "var zoomflag = 1;\n";
  my $sendstatsjs = "var sendstats = [];\n";
  $sendstatsjs   .= "sendstats['min'] = $sendstats[0];\n";
  $sendstatsjs   .= "sendstats['max'] = $sendstats[1];\n";
  $sendstatsjs   .= "sendstats['avg'] = $sendstats[2];\n";
  my $recvstatsjs = "var recvstats = [];\n";
  $recvstatsjs   .= "recvstats['min'] = $recvstats[0];\n";
  $recvstatsjs   .= "recvstats['max'] = $recvstats[1];\n";
  $recvstatsjs   .= "recvstats['avg'] = $recvstats[2];\n";
  if (not $args{zoom}) {
    $zoomjs = "var zoomflag = 0;\n";
    $sendimgjs = "var sendimgjs = [];\n";
    $recvimgjs = "var recvimgjs = [];\n";
  }
  my ($node_count, $rankmapjs) = return_rankmapjs(\%sendtable);
  my $factor = 1;
  while($factor * $node_count < 100) { $factor *= 2; }
  print HTML "
var border = 1;
var width  = $factor;
var count  = $node_count;
$zoomjs
$sendstatsjs
$recvstatsjs
$rankmapjs
$sendimgjs
$recvimgjs
var tooltip;
";
  print HTML '
function loading() {
  var sendimg = document.getElementById("send_img");
  sendimg.onmousemove=sendtrack;
  sendimg.onmouseout=hidetip;
  var recvimg = document.getElementById("recv_img");
  recvimg.onmousemove=recvtrack;
  recvimg.onmouseout=hidetip;

  tooltip = document.createElement("div");
  tooltip.style.visibility = "hidden";
  document.body.appendChild(tooltip);
}

function sendtrack(e) {
  var img  = document.getElementById("send_img");
  var zoom = document.getElementById("send_zoom");
  track(e,img," ==> ",sendimgjs,sendstats["max"],zoom);
}

function recvtrack(e) {
  var img  = document.getElementById("recv_img");
  var zoom = document.getElementById("recv_zoom");
  track(e,img," <== ",recvimgjs,recvstats["max"],zoom);
}

function track(e,img,dir,imgjs,max,zoom) {
  var relX = e.pageX - img.offsetLeft;
  var relY = e.pageY - img.offsetTop;
  var col = Math.floor((relX - border) / width);
  var row = Math.floor((relY - border) / width);

  document.body.style.cursor = "crosshair";

  if (row >= 0 && col >= 0 && row < count && col < count) {
    if (zoomflag) {
      var pixval = imgjs[(count*width)-1-row*width][col*width];
      var bw     = Math.round((max * pixval) / 255);
      tooltip.innerHTML = \'<div style="background-color: #AAFFFF;border: solid 1px; font-size: large;">\' +
	"(" + relX + ", " + relY + ")<br>" +
	rankmap[row] + dir + rankmap[col] + "<br>" + bw + " MB/sec" + "<br>Measured by: " + rankmap[row] +
	zoomed(row,col,imgjs,dir,max) + \'</div>\';
    } else {
      tooltip.innerHTML = \'<div style="background-color: #AAFFFF;border: solid 1px; font-size: large;">\' +
	"(" + relX + ", " + relY + ")<br>" +
	rankmap[row] + dir + rankmap[col] + "<br>Measured by: " + rankmap[row] +
	\'</div>\';
    }
    tooltip.style.position = "absolute";
    tooltip.style.left = e.pageX + 20;
    tooltip.style.top    = "";
    tooltip.style.bottom = "";
    if ((e.pageY-window.pageYOffset) < window.innerHeight / 2) {
      tooltip.style.top = e.pageY + 20;
    } else {
      tooltip.style.bottom = window.innerHeight - e.pageY + 20;
    }
    tooltip.style.visibility = "visible"; 
  } else {
    hidetip();
  }
}

function hidetip() {
  tooltip.style.visibility = "hidden";
  document.body.style.cursor = "auto";
}

function zoomed(row,col,imgjs,dir,max) {
  var rows = "";
  var pad = 5;
  var header = "<td></td>";
  for(c=pad*2; c>=0; c--) {
    //var c2 = col*width+pad-c;
    //header += "<td style=\"background-color:#AAFFFF;\">" + rankmap[Math.floor(c2/width)] + "</td>";
    var c2 = col+pad-c;
    header += "<td style=\"background-color:#AAFFFF;\">" + rankmap[c2] + "</td>";
  }
  header = "<tr>" + header + "</tr>\n";
  for(r=pad*2; r>=0; r--) {
    var cell = "";
    for(c=pad*2; c>=0; c--) {
      //var r2 = row*width+pad-r;
      //var c2 = col*width+pad-c;
      var r2 = row*width+(pad-r)*width;
      var c2 = col*width+(pad-c)*width;
      if (r2 >= 0 && c2 >= 0 && r2 < count*width && c2 < count*width) {
        var pixval = imgjs[(count*width)-1-r2][c2];
        var bw     = Math.round((max * pixval) / 255);
        var color  = (pixval < 128) ? "color: #FFFFFF;" : "";
        var border = (r == pad && c == pad) ? "border: solid 2px #FF0000;" : "";
        cell += "<td style=\"background-color: rgb(" + pixval + "," + pixval + "," + pixval + ");" + color + border + "\">" + bw + "</td>";
      } else {
        cell += "<td></td>";
      }
    }
    rows += "<tr>" + "<td style=\"background-color:#AAFFFF\">" 
            + rankmap[Math.floor(r2/width)] + dir + cell + "</td></tr>\n"; 
  }
  return "<table>" + header + rows + "</table>";
}
';
  print HTML "</script>\n";

  # now write out main body starting with header
  print HTML "<body onload=\"loading();\">\n";
  print HTML "<h1>mpiGraph Details</h1>\n";
  print HTML "<table>\n";
  print HTML "<tr><td>Date:</td><td>" . localtime($testtime) . "</td></tr>\n";
  my ($hostcount, $hoststr) = output_rankmap(\%sendtable, "$dir/map.txt");
  print HTML "<tr><td>Nodes:</td><td>" . $hostcount . "</td></tr>\n";
  print HTML "<tr><td>Node list:</td><td>" . $hoststr . "</td></tr>\n";
  my $passwd = `grep ":$testuser:" /etc/passwd`;
  my @parts = split(":", $passwd);
  print HTML "<tr><td>Run by:</td><td>" . $parts[0] . " (" . $parts[4]. ")</td></tr>\n";
  print HTML "<tr><td>MsgSize:</td><td>$msgsize</td></tr>\n";
  print HTML "<tr><td>Times:</td><td>$times</td></tr>\n";
  print HTML "<tr><td>Window:</td><td>$window</td></tr>\n";
  print HTML "</table><br>\n";
  print HTML "<a href=\"map.txt\">MPI rank to node mapping</a><br>";

  my ($min, $max, $avg);

  # write out send bandwidth portion
  print HTML "<h1>Send Bandwidth</h1>\n";
  print HTML "<table border=\"1\">\n<tr><td>min MB/s</td><td>max MB/s</td><td>avg MB/s</td></tr>\n";
  ($min, $max, $avg) = @sendstats;
  print HTML "<tr><td>$min</td><td>$max</td><td>$avg</td>";
  ($min, $max, $avg) = @sendpercs;
  print HTML "<tr><td>$min</td><td>$max</td><td>$avg</td>";
  print HTML "</tr>\n</table>\n";
  print HTML "<img id=\"send_img\" src=\"send.bmp\" border=\"1\"/>";
  print HTML "<img src=\"send_hist.png\" border=\"1\"/>";
  print HTML "<div id=\"send_zoom\"></div>\n";

  # write out recv bandwidth portion
  print HTML "<h1>Receive Bandwidth</h1>\n";
  print HTML "<table border=\"1\"><tr><td>min MB/s</td><td>max MB/s</td><td>avg MB/s</td></tr>\n";
  ($min, $max, $avg) = @recvstats;
  print HTML "<tr><td>$min</td><td>$max</td><td>$avg</td>";
  ($min, $max, $avg) = @recvpercs;
  print HTML "<tr><td>$min</td><td>$max</td><td>$avg</td>";
  print HTML "</tr>\n</table>\n";
  print HTML "<img id=\"recv_img\" src=\"recv.bmp\" border=\"1\"/>\n";
  print HTML "<img src=\"recv_hist.png\" border=\"1\"/>\n";
  print HTML "<div id=\"recv_zoom\"></div>\n";

  # close index.html
  print HTML "</body></html>";
  close(HTML);

  # create histogram images
  `cat $dir/recv.bmp | anytopnm | ppmtopgm | pnmhistmap | pnmtopng > $dir/recv_hist.png`;
  `cat $dir/send.bmp | anytopnm | ppmtopgm | pnmhistmap | pnmtopng > $dir/send_hist.png`;

  # write out node performance pages
#  output_table(\%sendtable, "$dir/send.html", "$dir/send_rows_cols.html", @sendstats);
#  output_table(\%recvtable, "$dir/recv.html", "$dir/recv_rows_cols.html", @recvstats);

  my $pwd = `pwd`;
  chomp $pwd;
  print "Report complete:  firefox file://$pwd/$dir/index.html\n";
}

# this reads in an mpiGraph output file and fills sendtable and recvtable
# it returns the parameters used to run the job and the time the file was created
sub read_file
{
  my $file      = shift @_;
  my $sendtable = shift @_;
  my $recvtable = shift @_;

  print "Reading $file...\n";
  my $sendflag = 0;
  my $recvflag = 0;
  open(IN,$file);
  while (my $line = <IN>)
  {
    chomp $line;

    # empty lines indicate end of table
    if (not $line) {
      $sendflag = 0;
      $recvflag = 0;
    }

    my @parts = split('\t', $line);

    # process header info, may start read of table data
    if    ($line =~ /MsgSize\t/) { $msgsize = $parts[1]; next; }
    elsif ($line =~ /Times\t/)   { $times   = $parts[1]; next; }
    elsif ($line =~ /Window\t/)  { $window  = $parts[1]; next; }
    elsif ($line =~ /Send\t/) { $sendflag = 1; @colnames = @parts; next; }
    elsif ($line =~ /Recv\t/) { $recvflag = 1; @colnames = @parts; next; }

    # if reading table, read in next row
    if ($sendflag or $recvflag) {
      $rh = $parts[0];
      $rh =~ s/[a-zA-Z\s]*$//; # strip off trailing letters and spaces
      $rh =~ s/^\s*\d+://;     # strip off leading spaces and [0-9]+:
      if ($strip_mpi_rank) { $rh =~ s/:\d+$//; } # remove mpi rank from node name
#TODO: hack to remove suffix starting with '-'
#print "-- $rh -- ";
      $rh =~ s/\-\w*$//;     # strip off trailing prefix starting with '-'
#print "-- $rh -- \n";
      for(my $i = 1; $i < @parts; $i++) {
        $ch = $colnames[$i];
        if ($strip_mpi_rank) { $ch =~ s/:\d+$//; } # remove mpi rank from node name
        $ch =~ s/\-\w*$//;     # strip off trailing prefix starting with '-'
        if ($sendflag) { push @{$$sendtable{$rh}{$ch}}, $parts[$i]; }
        if ($recvflag) { push @{$$recvtable{$rh}{$ch}}, $parts[$i]; }
      }
    }
  }
  close(IN);

  return $msgsize, $times, $window, (stat($file))[4,9];
}

# return avg of a list of numbers
sub avg
{
  if (@_) {
    my $sum = 0;
    foreach my $val (@_) { $sum += $val; }
    return $sum / @_;
  }
}

# find min, max, and compute average of all values in table
sub min_max_avg
{
  my $table = shift @_;
  my $row = (keys %$table)[1];
  my $col = (keys %{$$table{$row}})[0];
  my $min = avg(@{$$table{$row}{$col}});
  my $max = avg(@{$$table{$row}{$col}});
  my $sum = 0;
  my $count = 0;
  foreach my $row (sort keys %$table) {
    foreach my $col (sort keys %{$$table{$row}}) {
      if ($col eq $row) { next; }
      my $value = avg(@{$$table{$row}{$col}});
      if ($value < $min) { $min = $value; }
      if ($value > $max) { $max = $value; }
      $sum += $value;
      $count++;
    }
  }
  my $avg = $sum / $count;
  $min = sprintf("%0.3f", $min);
  $max = sprintf("%0.3f", $max);
  $avg = sprintf("%0.3f", $avg);
  return ($min, $max, $avg);
}

# output mapping of MPI rank to nodename
sub output_rankmap
{
  my $table = shift @_;
  my $outfile = shift @_;
  print "Writing $outfile ...\n";
  open(MAP, ">$outfile");
  print MAP "Rank\tNode\n";
  my @nodes = ();
  my @rows = keys %$table;
  @rows = (sort {($a =~ /(\d+)$/)[0] <=> ($b =~ /(\d+)$/)[0]} @rows);
  $rank = -1;
  foreach $row (@rows)
  {
    if ($strip_mpi_rank) { ($node) = ($row =~ /([a-zA-Z]+\d*)/); $rank++; }
    else { ($node, $rank) = ($row =~ /([a-zA-Z]+\d*):(\d+)/); }
    if ($node) {
      print MAP "$rank\t$node\n";
      push @nodes, $node;
    }
  }
  close(MAP);
#  my $nodelist = join(",", @nodes);  # if you don't have compress(), use this instead
  my $nodelist = hostlist_lite::compress(@nodes);
  return (scalar(@nodes), $nodelist);
}

# write out bandwidth table
# and average across rows and down columns for html report
sub output_table
{
  my $table   = "";
  my $outfile = "";
  my $outfile_rows_cols = "";
  my @stats = ();

  if ($mode eq "html") {
    $table   = shift @_;
    $outfile = shift @_;
    $outfile_rows_cols = shift @_;
    @stats   = @_;
  } else {
    $table = shift @_;
    @stats = @_;
  }
  if (not $outfile_rows_cols) { $outfile_rows_cols = $outfile; }

  print "Writing $outfile_rows_cols ...\n";
  my ($min, $max, $avg) = @stats;
  if ($mode eq "html") {
    open(OUT, ">$outfile");
    print OUT table((
	row((cell("Min"), cell("Max"), cell("Avg"))),
        row((cell($min),  cell($max),  cell($avg))),
    ));
    close(OUT);
  }

  my @outrows = ();
  my %rowsum = ();
  my %colsum = ();
  my @rows = keys %$table;
  @rows = (sort {($a =~ /(\d+)$/)[0] <=> ($b =~ /(\d+)$/)[0]} @rows);
  my @cols = @rows;
  my $row_count = scalar(@rows);
  foreach my $r (@rows) {
    $rowsum{$r} = 0;
    $colsum{$r} = 0;
  }
  my $row_index = 0;
  foreach my $r (@rows)
  {
    my @outcells = ();
    foreach my $c (@cols)
    {
      my $row = $r;
      my $col = $c;
      $row =~ s/:[\w\s]*$//;
      $col =~ s/:[\w\s]*$//;
      my $val = avg(@{$$table{$r}{$c}});
      if ($row eq $col) {
        $color = "";
      } else {
        $perf  = $val / $max;
        $color = set_color($perf);
        $rowsum{$r} += $perf;
        $colsum{$c} += $perf;
      }
      push @outcells, cell($val, $color);
    }
    if ($args{dist}) {
      for(my $s = 0; $s < $row_index; $s++) { my $temp = shift @outcells; push @outcells, $temp; }
    }
    push @outrows, row(@outcells);
    $row_index++;
  }
  if ($mode eq "html")   {
    my $br = "<br>\n";
    open (OUT, ">$outfile_rows_cols");

    print OUT "<a href=\"#slowest\">Ordered by slowest-to-fastest</a><br>\n";
    print OUT "<a href=\"#mpi_rank\">Ordered by MPI rank</a><br>\n";

    print OUT $br;

    my @slowestrows = (sort {$rowsum{$a} <=> $rowsum{$b}} keys %rowsum); 
    my @slowestcols = (sort {$colsum{$a} <=> $colsum{$b}} keys %colsum); 
    my $minrow = sprintf("%0.1f", $rowsum{$slowestrows[ 0]} * 100 / ($row_count));
    my $maxrow = sprintf("%0.1f", $rowsum{$slowestrows[-1]} * 100 / ($row_count));
    my $mincol = sprintf("%0.1f", $colsum{$slowestcols[ 0]} * 100 / ($row_count));
    my $maxcol = sprintf("%0.1f", $colsum{$slowestcols[-1]} * 100 / ($row_count));
    print OUT "Minimum and maximum performance" . $br;
    print OUT "<table border=\"1\">\n";
    print OUT "<tr><td>Min Row \%Max</td><td>Max Row \%Max</td><td>Min Col \%Max</td><td>Max Col \%Max</td></tr>\n";
    print OUT "<tr><td>$minrow\%</td><td>$maxrow\%</td><td>$mincol\%</td><td>$maxcol\%</td></tr>\n";
    print OUT "</table>\n";

    print OUT $br, $br;

    # print average across row and column for each rank, in order of slowest to fastest
    print OUT "<a name=\"slowest\"/>\n";
    print OUT "Ordered by slowest-to-fastest" . $br;
    print OUT "<table border=\"1\">\n";
    print OUT "<tr><td>Row</td><td>avg MB/s</td><td>\%Max</td><td>Column</td><td>avg MB/s</td><td>\%Max</td></tr>\n";
    for(my $r = 0; $r < @slowestrows; $r++)
    {
      print OUT "<tr>";
      my $i = $slowestrows[$r];
      $perf = $rowsum{$i} / ($row_count); 
      $perf = sprintf("%0.4f", $perf);
      $bw   = sprintf("%0.1f", $perf*$max);
      $perc = sprintf("%0.1f", $perf*100);
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $i    . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $bw   . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $perc . "%</td>";

      $i = $slowestcols[$r];
      $perf = $colsum{$i} / ($row_count); 
      $perf = sprintf("%0.4f", $perf);
      $bw   = sprintf("%0.1f", $perf*$max);
      $perc = sprintf("%0.1f", $perf*100);
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $i    . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $bw   . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $perc . "%</td>";
      print OUT "</tr>\n";
    }
    print OUT "</table>\n"; 

    print OUT "<br><br>\n";

    # print average across row and column for each rank, in order of MPI ranks
    print OUT "<a name=\"mpi_rank\"/>\n";
    print OUT "Ordered by MPI rank" . $br;
    print OUT "<table border=\"1\">\n";
    print OUT "<tr><td>Row</td><td>avg MB/s</td><td>\%Max</td><td>Column</td><td>avg MB/s</td><td>\%Max</td></tr>\n";
    for(my $r = 0; $r < @rows; $r++)
    {
      print OUT "<tr>";
      my $i = $rows[$r];
      $perf = $rowsum{$i} / ($row_count); 
      $perf = sprintf("%0.4f", $perf);
      $bw   = sprintf("%0.1f", $perf*$max);
      $perc = sprintf("%0.1f", $perf*100);
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $i    . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $bw   . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $perc . "%</td>";

      $perf = $colsum{$i} / ($row_count); 
      $perf = sprintf("%0.4f", $perf);
      $bw   = sprintf("%0.1f", $perf*$max);
      $perc = sprintf("%0.1f", $perf*100);
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $i    . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $bw   . "</td>";
      print OUT "<td bgcolor=\"" . set_color($perf) . "\">" . $perc . "</td>";
      print OUT "</tr>\n";
    }
    print OUT "</table>\n"; 

    close(OUT);
  } else {
    print table(@outrows) . "\n";
    print "\n";
  }
}

# convert table to a list of rows, each with comma-separated values
# then call write_bitmap() function to write bitmap file
sub output_table_bitmap
{
  my $table   = shift @_;
  my $outfile = shift @_;
  my @stats   = @_;

  print "Writing $outfile ...\n";
  my @outrows = ();
  my ($min, $max, $avg) = @stats;
  if ($maxbw) { $max = $maxbw; }
  my @rows = keys %$table;
  @rows = (sort {($a =~ /(\d+)$/)[0] <=> ($b =~ /(\d+)$/)[0]} @rows);
  @cols = @rows;
  my $row_index = 0;
  foreach $row (@rows) {
    my @outcells = ();
    foreach $col (@cols) {
      if ($row eq $col) {
        $perf = 1;
      } else {
        my $value = avg(@{$$table{$row}{$col}});
        $perf = $value / $max;
        if ($perf < 0.0) { print "ERROR: avg bw < 0: " .      join(", ", @{$$table{$row}{$col}}), "\n"; }
        if ($perf > 1.0) { print "ERROR: avg bw > max bw: " . join(", ", @{$$table{$row}{$col}}), "\n"; }
      }
      if ($perf > 1.0) {
        print "ERROR: $perf > 1.0, setting to 1.0 and continuing ... \n";
        $perf = 1.0;
      }
      if ($perf < 0) {
        print "ERROR: $perf < 0.0, setting to 0.0 and continuing ... \n";
        $perf = 0.0;
      }
      $color = int($perf * 255);
      push @outcells, $color;
    }
    if ($args{dist}) {
      for(my $s = 0; $s < $row_index; $s++) { my $temp = shift @outcells; push @outcells, $temp; }
    }
    push @outrows, join(",", @outcells);
    $row_index++;
  }
  write_bitmap($outfile, @outrows);
}

# write_bitmap(filename, @rows with comma-delimited column values)
sub write_bitmap
{
  my $bmpfile = shift @_;
  my @rows = @_;
  my @vals = split(',', $rows[0]);

  # get data dimensions
  my $height = scalar(@rows);
  my $width  = scalar(@vals);

  # create an image that is at least 100 pixels
  my $factor = 1;
  while ($factor * $height < 100) { $factor *= 2; }
  my $height_scaled = $height * $factor;
  my $width_scaled  = $width  * $factor;

  # bitmap rows must have a byte count that is a multiple of 4
  # pad it out if necessary (this data won't be displayed)
  my $pad = ($width_scaled * 3) % 4;
  if ($pad > 0) { $pad = 4 - $pad; }

  my $filesize = $width_scaled * $height_scaled * 3 + 54;
  print "Writing $bmpfile ($width_scaled x $height_scaled) bitmap, $filesize bytes ...\n";

  # bitmap file format:  see http://www.fortunecity.com/skyscraper/windows/364/bmpffrmt.html
  # open a file in binary mode and print bitmap file header
  open(OUT, ">$bmpfile");
  binmode(OUT);
  print OUT "BM";
  print OUT pack "I", $filesize;
  print OUT pack "xx";
  print OUT pack "xx";
  print OUT pack "I", 54;
  print OUT pack "III", 40, $width_scaled, $height_scaled;
  print OUT pack "SS", 1, 24;
  print OUT pack "IIIIII", 0, 0, 0, 0, 0, 0;

  # print the pixel values
  @imagerows = (); # store pixel values to be printed in javascript notation (json)
  # run down the rows
  for ($y = $height-1; $y >= 0; $y--) {
    my $row = $rows[$y];
    chomp $row;
    my @vals = split(',', $row);
    # may use more than one pixel per data point depending on minimum image size
    for ($j = 0; $j < $factor; $j++) {
      my @imagerow = ();
      # print column values for this row
      for ($x = 0; $x < $width; $x++) {
        my $col = $vals[$x];
        # may use more than one pixel per data point depending on minimum image size
        for ($i = 0; $i < $factor; $i++) {
          if ($col >= 256 or $col < 0) { print "ERROR: Invalid pixel value: $col\n"; }
          print OUT pack "CCC", $col, $col, $col;
          push @imagerow, $col;
        }
      }
      # pad out the row if necessary
      for($p=0; $p < $pad; $p++) {
        $col = 0;
        print OUT pack "C", $col;
      }
      push @imagerows, "[" . join(",", @imagerow) . "]";
    }
  }
  close(OUT);
}

# given a table reference, returns array of node names in javascript (json)
sub return_rankmapjs
{
  my $table = shift @_;
  my @rows = keys %$table;
  @rows = (sort {($a =~ /(\d+)$/)[0] <=> ($b =~ /(\d+)$/)[0]} @rows);
  my @nodes = ();
  my $node = "";
  my $rank = "";
  foreach my $row (@rows) {
    if ($strip_mpi_rank) { ($node) = ($row =~ /([a-zA-Z\-]+\d*)/); $rank++; }
    else { ($node, $rank) = ($row =~ /([a-zA-Z\-]+\d*):(\d+)/); }
    if ($node) { push @nodes, '"' . $node . '"'; }
  }
  return (scalar(@nodes), "var rankmap = [" . join(",", @nodes) . "];");
}

# returns color string for a value from [0,1]
sub set_color
{
  my $val = shift @_;
  if ($mode eq "html") {
    # just use grayscale in html
    my $gray = sprintf("%x", int($val*255));
    return "#" . $gray . $gray . $gray;
  } else {
    return "";
  }

  my $len = scalar(@$legend);
  for($i=0; $i<$len; $i += 2) {
    if ($val < $$legend[$i]) { return $$legend[$i+1]; }
  }
  return $$legend[$len-1];
}

# given the contents and color for a cell,
# return a string representing the colored cell
sub cell
{
  my $content = shift @_;
  my $color   = shift @_;

  my $spacing = 10;
  my $maxlen  = 100;
  my $len     = length($content);
  my $extra = ($len < $spacing) ? $spacing - $len : 0;
  if ($mode ne "html")
  {
    $content = ' ' x $extra . $content;
    $len = length($content);
    $offset = ($len > $maxlen) ? $len - $maxlen : 0;
    $content = substr($content, $offset);
  }
  if ($mode eq "html") {
    if ($color) { return "<td bgcolor=\"" . $color . "\">$content</td>"; }
    return "<td>$content</td>";
  } else {
    return $content;
  }
}

# given a list of cells, return a string representing the row
sub row
{
  if ($mode eq "html") {
    return "<tr>" . join("", @_) . "</tr>";
  } else {
    return join("\t", @_);
  }
}

# given a list of rows, return a string representing the table
sub table
{
  if ($mode eq "html") {
    return "<table border=\"1\">\n" . join("\n", @_) . "\n</table>\n";
  } else {
    return join("\n", @_) . "\n";
  }
}