Repeated performance measurements for r1373 and the code on this branch.

Repeated performance measurements for r1373 and the code on this branch.
Results: identical throughput for all test cases, except for 128K and 8K
asynchronous writes, where the implementation on the branch performs 19%
and 15% faster than r1373 respectively.

Setup details for the target:
* 2.6.30.7 kernel with SCST patches and with kernel debugging disabled.
* SCST revision compiled in release mode (make debug2release).
* ib_srpt kernel module parameters thread=0.
* 1 GB file residing on a tmpfs filesystem was exported via scst_vdisk.
* Frequency scaling was disabled.
* Runlevel: 3.

Setup details for the initiator:
* vanilla 2.6.27.39 kernel.
* SRP initiator was loaded with parameter srp_sg_tablesize=128
* Frequency scaling was disabled.
* Runlevel: 3.

Results for SCST r1373:

$ ~bart/software/scst/scripts/blockdev-perftest -d -s 30 -m 12 /dev/sdb
blocksize        W        W        W   W(avg,   W(std,        W        R        R        R   R(avg,   R(std,        R
  (bytes)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)
 67108864    1.223    1.223    1.225  836.768    0.736   13.075    0.595    0.595    0.595 1720.680    0.851   26.886
 33554432    1.210    1.210    1.210  846.088    0.088   26.440    0.606    0.605    0.606 1690.110    1.920   52.816
 16777216    1.185    1.185    1.185  864.121    0.248   54.008    0.622    0.622    0.623 1645.466    1.497  102.842
  8388608    1.135    1.129    1.132  904.632    1.878  113.079    0.649    0.652    0.652 1572.881    3.051  196.610
  4194304    1.040    1.045    1.043  982.054    1.918  245.513    0.696    0.694    0.695 1472.949    1.982  368.237
  2097152    1.098    1.097    1.096  933.543    0.490  466.772    0.767    0.768    0.764 1335.724    2.799  667.862
  1048576    1.265    1.264    1.265  809.638    0.367  809.638    0.901    0.908    0.900 1134.238    4.161 1134.238
   524288    1.501    1.506    1.502  681.378    0.931 1362.756    1.117    1.125    1.124  912.656    2.814 1825.313
   262144    1.668    1.662    1.661  615.442    1.206 2461.770    1.235    1.230    1.234  830.492    1.361 3321.970
   131072    1.860    1.851    1.855  551.951    1.083 4415.610    1.282    1.274    1.276  801.575    2.029 6412.599
    65536    2.236    2.245    2.238  457.248    0.797 7315.963    1.613    1.622    1.608  634.377    2.323 10150.035
    32768    3.065    3.062    3.078  333.698    0.732 10678.340    2.283    2.274    2.273  449.759    0.945 14392.298
    16384    4.706    4.794    4.716  216.114    1.779 13831.324    3.662    3.645    3.645  280.513    0.609 17952.809
     8192    8.097    8.237    8.096  125.752    1.017 16096.212    6.297    6.302    6.289  162.640    0.134 20817.981
     4096   14.674   14.694   14.657   69.780    0.071 17863.608   11.449   11.440   11.408   89.570    0.139 22929.974
$ ~bart/software/scst/scripts/blockdev-perftest -a -s 30 -m 12 /dev/sdb
blocksize        W        W        W   W(avg,   W(std,        W        R        R        R   R(avg,   R(std,        R
  (bytes)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)
 67108864    1.701    1.705    1.699  601.771    0.822    9.403    1.709    1.728    1.728  594.774    3.119    9.293
 33554432    1.695    1.618    1.603  625.428   15.196   19.545    1.719    1.720    1.723  595.142    0.687   18.598
 16777216    1.600    1.598    1.598  640.423    0.436   40.026    1.741    1.720    1.722  592.707    3.291   37.044
  8388608    1.809    1.807    1.568  595.301   40.790   74.413    1.706    1.705    1.705  600.468    0.156   75.058
  4194304    1.314    1.314    1.551  739.690   56.260  184.922    1.628    1.634    1.629  628.190    0.951  157.048
  2097152    1.040    0.981    1.189  963.138   75.904  481.569    1.407    1.426    1.425  721.444    4.347  360.722
  1048576    1.064    0.995    1.067  983.835   32.288  983.835    1.285    1.277    1.286  798.358    2.347  798.358
   524288    0.984    1.058    0.987 1015.093   33.379 2030.187    1.252    1.254    1.250  817.791    1.280 1635.582
   262144    0.986    0.982    1.153  989.944   71.807 3959.778    1.243    1.249    1.244  822.357    1.723 3289.428
   131072    1.155    1.160    1.160  883.882    1.666 7071.055    1.251    1.252    1.252  818.046    0.179 6544.368
    65536    0.928    0.928    1.166 1028.366  106.412 16453.859    1.262    1.254    1.255  814.735    2.217 13035.757
    32768    1.183    1.084    1.084  918.281   37.291 29385.000    1.260    1.262    1.257  812.726    1.254 26007.237
    16384    0.930    1.178    0.931 1023.755  109.140 65520.309    1.266    1.270    1.269  807.233    1.189 51662.925
     8192    1.203    1.101    1.112  900.865   35.135 115310.778    1.273    1.274    1.272  804.366    0.725 102958.849
     4096    0.999    1.094    1.093  966.038   41.681 247305.603    1.293    1.293    1.293  792.081    0.136 202772.806

Results for the SCST code on this branch:

$ ~bart/software/scst/scripts/blockdev-perftest -d -s 30 -m 12 /dev/sdb
blocksize        W        W        W   W(avg,   W(std,        W        R        R        R   R(avg,   R(std,        R
  (bytes)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)
 67108864    1.220    1.225    1.220  838.049    1.672   13.095    0.595    0.595    0.596 1720.849    0.929   26.888
 33554432    1.208    1.207    1.210  847.223    0.909   26.476    0.603    0.603    0.604 1697.318    1.800   53.041
 16777216    1.180    1.181    1.179  867.755    0.626   54.235    0.619    0.619    0.619 1654.679    0.375  103.417
  8388608    1.127    1.130    1.128  907.754    1.025  113.469    0.649    0.649    0.650 1577.987    1.350  197.248
  4194304    1.041    1.043    1.084  970.038   17.898  242.509    0.745    0.691    0.691 1446.033   50.051  361.508
  2097152    1.096    1.097    1.097  933.846    0.127  466.923    0.770    0.769    0.768 1331.667    1.308  665.834
  1048576    1.268    1.282    1.269  804.454    3.912  804.454    0.912    0.909    0.910 1125.005    1.691 1125.005
   524288    1.518    1.519    1.518  674.360    0.179 1348.720    1.132    1.133    1.127  905.460    2.061 1810.919
   262144    1.686    1.687    1.685  607.410    0.289 2429.640    1.234    1.233    1.235  829.988    0.750 3319.953
   131072    1.845    1.855    1.849  553.648    1.199 4429.182    1.281    1.271    1.270  803.701    3.236 6429.607
    65536    2.243    2.238    2.250  456.401    0.958 7302.419    1.610    1.609    1.615  635.507    1.152 10168.115
    32768    3.100    3.096    3.101  330.442    0.191 10574.158    2.281    2.273    2.276  449.770    0.680 14392.647
    16384    4.730    4.738    4.781  215.603    1.015 13798.570    3.668    3.658    3.630  280.404    1.249 17945.853
     8192    8.136    8.143    8.125  125.879    0.117 16112.492    6.310    6.288    6.320  162.386    0.343 20785.421
     4096   14.734   14.777   14.729   69.440    0.102 17776.731   11.434   11.434   11.421   89.591    0.051 22935.343
$ ~bart/software/scst/scripts/blockdev-perftest -a -s 30 -m 12 /dev/sdb
blocksize        W        W        W   W(avg,   W(std,        W        R        R        R   R(avg,   R(std,        R
  (bytes)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)      (s)      (s)      (s)    MB/s)    MB/s)   (IOPS)
 67108864    1.621    1.616    1.859  605.258   38.591    9.457    1.733    1.732    1.730  591.217    0.421    9.238
 33554432    1.606    1.849    1.608  609.432   39.346   19.045    1.748    1.727    1.781  584.599    7.431   18.269
 16777216    1.613    1.615    1.838  608.666   36.341   38.042    1.726    1.723    1.732  592.885    1.307   37.055
  8388608    1.806    1.808    1.598  591.362   34.824   73.920    1.713    1.711    1.710  598.426    0.454   74.803
  4194304    1.555    1.332    1.543  696.900   50.708  174.225    1.633    1.685    1.642  619.381    8.436  154.845
  2097152    0.966    0.966    0.957 1063.283    5.105  531.642    1.413    1.409    1.415  724.960    1.347  362.480
  1048576    1.166    0.933    1.173  949.570  104.943  949.570    1.276    1.278    1.280  801.318    0.890  801.318
   524288    0.930    0.930    1.158 1028.986  102.433 2057.971    1.253    1.253    1.255  816.704    0.517 1633.409
   262144    0.993    0.958    1.167  992.704   83.077 3970.817    1.242    1.243    1.244  823.968    0.476 3295.873
   131072    0.998    0.994    0.932 1051.674   33.625 8413.395    1.256    1.251    1.251  817.434    1.742 6539.470
    65536    0.929    1.173    0.931 1025.243  107.612 16403.886    1.250    1.254    1.253  817.667    1.190 13082.667
    32768    0.933    1.185    1.182  942.734  109.764 30167.481    1.266    1.268    1.262  809.419    1.637 25901.411
    16384    1.174    1.006    1.008  968.451   68.247 61980.887    1.262    1.267    1.269  808.751    1.941 51760.085
     8192    1.041    0.990    0.934 1037.960   45.831 132858.894    1.270    1.310    1.274  797.260   10.946 102049.295
     4096    1.287    1.000    1.001  947.597  107.493 242584.705    1.294    1.309    1.287  789.841    5.665 202199.350

git-svn-id: https://scst.svn.sourceforge.net/svnroot/scst/trunk@1483 d57e44dd-8a1f-0410-8b47-8ef2f437770f