Hi folks,
  I am attaching the bash helper scripts I used to run and post-process hackbench
in case you find them useful.  They compute the statistics and print a nicely
formatted result:

  feat - Enable/disable one or more sched_features.
  runmany - run a command many times and print average time and stdev.
  hackdiff - Print difference between 2 identical series of runmany hackbench runs.

You supply the top level script that runs a series of groups.  Example:

---- hackseries ---------------
#!/bin/sh

iters=50000
groups="1 2 3 4"
runs=5

tmpfile=temp$$.out
rm -f $tmpfile

runall() {
    for g in $groups ; do
        echo hackbench $g process $iters | tee -a $tmpfile
        runmany $runs hackbench $g process $iters | tee -a $tmpfile
    done
}

sudo feat NO_STEAL ; runall ; echo
sudo feat STEAL    ; runall ; echo
hackdiff < $tmpfile
rm -f $tmpfile
--------------------------------

$ hackseries
hackbench 1 process 50000
 4.096  4.090  4.073  4.129  4.092     Average 4.096   stdev 0.5%
hackbench 2 process 50000
 7.215  7.214  7.242  7.208  7.224     Average 7.220   stdev 0.2%
hackbench 3 process 50000
10.082 10.035 10.049 10.068 10.082     Average 10.063   stdev 0.2%
hackbench 4 process 50000
12.851 12.948 12.905 12.916 12.994     Average 12.922   stdev 0.4%

hackbench 1 process 50000
 3.193  3.261  3.257  3.223  3.247     Average 3.236   stdev 0.9%
hackbench 2 process 50000
 6.020  5.960  6.003  6.008  5.998     Average 5.997   stdev 0.4%
hackbench 3 process 50000
 8.598  8.692  8.536  8.661  8.468     Average 8.591   stdev 1.1%
hackbench 4 process 50000
11.201 11.148 11.053 11.174 11.127     Average 11.140   stdev 0.5%

          --- base --    --- new ---
groups    time %stdev    time %stdev  %speedup
     1   4.096    0.5   3.236    0.9      26.5
     2   7.220    0.2   5.997    0.4      20.3
     3  10.063    0.2   8.591    1.1      17.1
     4  12.922    0.4  11.140    0.5      15.9

- Steve