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 (a] denx.de> 91
