AMCC suggested to set the PMU bit to 0 for best performace on the
|
PPC440 DDR controller. The 440er common DDR setup files (sdram.c &
|
spd_sdram.c) are changed accordingly. So all 440er boards using
|
these setup routines will automatically receive this performance
|
increase.
|
|
Please see below some benchmarks done by AMCC to demonstrate this
|
performance changes:
|
|
|
----------------------------------------
|
SDRAM0_CFG0[PMU] = 1 (U-Boot default for Bamboo, Yosemite and Yellowstone)
|
----------------------------------------
|
Stream benchmark results
|
-------------------------------------------------------------
|
This system uses 8 bytes per DOUBLE PRECISION word.
|
-------------------------------------------------------------
|
Array size = 2000000, Offset = 0
|
Total memory required = 45.8 MB.
|
Each test is run 10 times, but only
|
the *best* time for each is used.
|
-------------------------------------------------------------
|
Your clock granularity/precision appears to be 1 microseconds.
|
Each test below will take on the order of 112345 microseconds.
|
(= 112345 clock ticks)
|
Increase the size of the arrays if this shows that you are not getting
|
at least 20 clock ticks per test.
|
-------------------------------------------------------------
|
WARNING -- The above is only a rough guideline.
|
For best results, please be sure you know the precision of your system
|
timer.
|
-------------------------------------------------------------
|
Function Rate (MB/s) RMS time Min time Max time
|
Copy: 256.7683 0.1248 0.1246 0.1250
|
Scale: 246.0157 0.1302 0.1301 0.1302
|
Add: 255.0316 0.1883 0.1882 0.1885
|
Triad: 253.1245 0.1897 0.1896 0.1899
|
|
|
TTCP Benchmark Results
|
ttcp-t: socket
|
ttcp-t: connect
|
ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000 tcp ->
|
localhost
|
ttcp-t: 16777216 bytes in 0.28 real seconds = 454.29 Mbit/sec +++
|
ttcp-t: 2048 I/O calls, msec/call = 0.14, calls/sec = 7268.57
|
ttcp-t: 0.0user 0.1sys 0:00real 60% 0i+0d 0maxrss 0+2pf 3+1506csw
|
|
----------------------------------------
|
SDRAM0_CFG0[PMU] = 0 (Suggested modification)
|
Setting PMU = 0 provides a noticeable performance improvement *2% to
|
5% improvement in memory performance.
|
*Improves the Mbit/sec for TTCP benchmark by almost 76%.
|
----------------------------------------
|
Stream benchmark results
|
-------------------------------------------------------------
|
This system uses 8 bytes per DOUBLE PRECISION word.
|
-------------------------------------------------------------
|
Array size = 2000000, Offset = 0
|
Total memory required = 45.8 MB.
|
Each test is run 10 times, but only
|
the *best* time for each is used.
|
-------------------------------------------------------------
|
Your clock granularity/precision appears to be 1 microseconds.
|
Each test below will take on the order of 120066 microseconds.
|
(= 120066 clock ticks)
|
Increase the size of the arrays if this shows that you are not getting
|
at least 20 clock ticks per test.
|
-------------------------------------------------------------
|
WARNING -- The above is only a rough guideline.
|
For best results, please be sure you know the precision of your system
|
timer.
|
-------------------------------------------------------------
|
Function Rate (MB/s) RMS time Min time Max time
|
Copy: 262.5167 0.1221 0.1219 0.1223
|
Scale: 258.4856 0.1238 0.1238 0.1240
|
Add: 262.5404 0.1829 0.1828 0.1831
|
Triad: 266.8594 0.1800 0.1799 0.1802
|
|
TTCP Benchmark Results
|
ttcp-t: socket
|
ttcp-t: connect
|
ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000 tcp ->
|
localhost
|
ttcp-t: 16777216 bytes in 0.16 real seconds = 804.06 Mbit/sec +++
|
ttcp-t: 2048 I/O calls, msec/call = 0.08, calls/sec = 12864.89
|
ttcp-t: 0.0user 0.0sys 0:00real 46% 0i+0d 0maxrss 0+2pf 120+1csw
|
|
|
2006-07-28, Stefan Roese <sr@denx.de>
|
