doc/README.440-DDR-performance

   1 AMCC suggested to set the PMU bit to 0 for best performace on the
   2 PPC440 DDR controller. The 440er common DDR setup files (sdram.c &
   3 spd_sdram.c) are changed accordingly. So all 440er boards using
   4 these setup routines will automatically receive this performance
   5 increase.
   6
   7 Please see below some benchmarks done by AMCC to demonstrate this
   8 performance changes:
   9
  10
  11 ----------------------------------------
  12 SDRAM0_CFG0[PMU] = 1 (U-Boot default for Bamboo, Yosemite and Yellowstone)
  13 ----------------------------------------
  14 Stream benchmark results
  15 -------------------------------------------------------------
  16 This system uses 8 bytes per DOUBLE PRECISION word.
  17 -------------------------------------------------------------
  18 Array size = 2000000, Offset = 0
  19 Total memory required = 45.8 MB.
  20 Each test is run 10 times, but only
  21 the *best* time for each is used.
  22 -------------------------------------------------------------
  23 Your clock granularity/precision appears to be 1 microseconds.
  24 Each test below will take on the order of 112345 microseconds.
  25    (= 112345 clock ticks)
  26 Increase the size of the arrays if this shows that you are not getting
  27 at least 20 clock ticks per test.
  28 -------------------------------------------------------------
  29 WARNING -- The above is only a rough guideline.
  30 For best results, please be sure you know the precision of your system
  31 timer.
  32 -------------------------------------------------------------
  33 Function      Rate (MB/s)   RMS time     Min time     Max time
  34 Copy:         256.7683       0.1248       0.1246       0.1250
  35 Scale:        246.0157       0.1302       0.1301       0.1302
  36 Add:          255.0316       0.1883       0.1882       0.1885
  37 Triad:        253.1245       0.1897       0.1896       0.1899
  38
  39
  40 TTCP Benchmark Results
  41 ttcp-t: socket
  42 ttcp-t: connect
  43 ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000  tcp  ->
  44 localhost
  45 ttcp-t: 16777216 bytes in 0.28 real seconds = 454.29 Mbit/sec +++
  46 ttcp-t: 2048 I/O calls, msec/call = 0.14, calls/sec = 7268.57
  47 ttcp-t: 0.0user 0.1sys 0:00real 60% 0i+0d 0maxrss 0+2pf 3+1506csw
  48
  49 ----------------------------------------
  50 SDRAM0_CFG0[PMU] = 0 (Suggested modification)
  51 Setting PMU = 0 provides a noticeable performance improvement *2% to
  52 5% improvement in memory performance.
  53 *Improves the Mbit/sec for TTCP benchmark by almost 76%.
  54 ----------------------------------------
  55 Stream benchmark results
  56 -------------------------------------------------------------
  57 This system uses 8 bytes per DOUBLE PRECISION word.
  58 -------------------------------------------------------------
  59 Array size = 2000000, Offset = 0
  60 Total memory required = 45.8 MB.
  61 Each test is run 10 times, but only
  62 the *best* time for each is used.
  63 -------------------------------------------------------------
  64 Your clock granularity/precision appears to be 1 microseconds.
  65 Each test below will take on the order of 120066 microseconds.
  66    (= 120066 clock ticks)
  67 Increase the size of the arrays if this shows that you are not getting
  68 at least 20 clock ticks per test.
  69 -------------------------------------------------------------
  70 WARNING -- The above is only a rough guideline.
  71 For best results, please be sure you know the precision of your system
  72 timer.
  73 -------------------------------------------------------------
  74 Function      Rate (MB/s)   RMS time     Min time     Max time
  75 Copy:         262.5167       0.1221       0.1219       0.1223
  76 Scale:        258.4856       0.1238       0.1238       0.1240
  77 Add:          262.5404       0.1829       0.1828       0.1831
  78 Triad:        266.8594       0.1800       0.1799       0.1802
  79
  80 TTCP Benchmark Results
  81 ttcp-t: socket
  82 ttcp-t: connect
  83 ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000  tcp  ->
  84 localhost
  85 ttcp-t: 16777216 bytes in 0.16 real seconds = 804.06 Mbit/sec +++
  86 ttcp-t: 2048 I/O calls, msec/call = 0.08, calls/sec = 12864.89
  87 ttcp-t: 0.0user 0.0sys 0:00real 46% 0i+0d 0maxrss 0+2pf 120+1csw
  88
  89
  90 2006-07-28, Stefan Roese <sr@denx.de>