1AMCC suggested to set the PMU bit to 0 for best performace on the 2PPC440 DDR controller. The 440er common DDR setup files (sdram.c & 3spd_sdram.c) are changed accordingly. So all 440er boards using 4these setup routines will automatically receive this performance 5increase. 6 7Please see below some benchmarks done by AMCC to demonstrate this 8performance changes: 9 10 11---------------------------------------- 12SDRAM0_CFG0[PMU] = 1 (U-Boot default for Bamboo, Yosemite and Yellowstone) 13---------------------------------------- 14Stream benchmark results 15------------------------------------------------------------- 16This system uses 8 bytes per DOUBLE PRECISION word. 17------------------------------------------------------------- 18Array size = 2000000, Offset = 0 19Total memory required = 45.8 MB. 20Each test is run 10 times, but only 21the *best* time for each is used. 22------------------------------------------------------------- 23Your clock granularity/precision appears to be 1 microseconds. 24Each test below will take on the order of 112345 microseconds. 25 (= 112345 clock ticks) 26Increase the size of the arrays if this shows that you are not getting 27at least 20 clock ticks per test. 28------------------------------------------------------------- 29WARNING -- The above is only a rough guideline. 30For best results, please be sure you know the precision of your system 31timer. 32------------------------------------------------------------- 33Function Rate (MB/s) RMS time Min time Max time 34Copy: 256.7683 0.1248 0.1246 0.1250 35Scale: 246.0157 0.1302 0.1301 0.1302 36Add: 255.0316 0.1883 0.1882 0.1885 37Triad: 253.1245 0.1897 0.1896 0.1899 38 39 40TTCP Benchmark Results 41ttcp-t: socket 42ttcp-t: connect 43ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000 tcp -> 44localhost 45ttcp-t: 16777216 bytes in 0.28 real seconds = 454.29 Mbit/sec +++ 46ttcp-t: 2048 I/O calls, msec/call = 0.14, calls/sec = 7268.57 47ttcp-t: 0.0user 0.1sys 0:00real 60% 0i+0d 0maxrss 0+2pf 3+1506csw 48 49---------------------------------------- 50SDRAM0_CFG0[PMU] = 0 (Suggested modification) 51Setting PMU = 0 provides a noticeable performance improvement *2% to 525% improvement in memory performance. 53*Improves the Mbit/sec for TTCP benchmark by almost 76%. 54---------------------------------------- 55Stream benchmark results 56------------------------------------------------------------- 57This system uses 8 bytes per DOUBLE PRECISION word. 58------------------------------------------------------------- 59Array size = 2000000, Offset = 0 60Total memory required = 45.8 MB. 61Each test is run 10 times, but only 62the *best* time for each is used. 63------------------------------------------------------------- 64Your clock granularity/precision appears to be 1 microseconds. 65Each test below will take on the order of 120066 microseconds. 66 (= 120066 clock ticks) 67Increase the size of the arrays if this shows that you are not getting 68at least 20 clock ticks per test. 69------------------------------------------------------------- 70WARNING -- The above is only a rough guideline. 71For best results, please be sure you know the precision of your system 72timer. 73------------------------------------------------------------- 74Function Rate (MB/s) RMS time Min time Max time 75Copy: 262.5167 0.1221 0.1219 0.1223 76Scale: 258.4856 0.1238 0.1238 0.1240 77Add: 262.5404 0.1829 0.1828 0.1831 78Triad: 266.8594 0.1800 0.1799 0.1802 79 80TTCP Benchmark Results 81ttcp-t: socket 82ttcp-t: connect 83ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000 tcp -> 84localhost 85ttcp-t: 16777216 bytes in 0.16 real seconds = 804.06 Mbit/sec +++ 86ttcp-t: 2048 I/O calls, msec/call = 0.08, calls/sec = 12864.89 87ttcp-t: 0.0user 0.0sys 0:00real 46% 0i+0d 0maxrss 0+2pf 120+1csw 88 89 902006-07-28, Stefan Roese <sr@denx.de> 91