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DDR 2 BW Utlization

Paul Joseph
Expert 2795 points
Other Parts Discussed in Thread: AM3352

DDR BW Utilization for 720MHZ uP and 532Mhz DDR2? Can I obtain numbers for this?

From presentations, I see for 500Mhz up, DDR 200Mhz, the Utilization is 633 Mhz.

 I would like to know what it would be for the speed above.

  • 0
    TI__Genius 9190 points

    hello,

    here are the performance numbers for 720MHz ARM and 266MHz DDR2 (266MHz is the speed that the AM335x DDR2 interface runs):

    bw_mem and lat_mem_rd from lmbench. Bw_mem measures throughput during read (rd), write(wr), read+write (rdwr) and copy (cp) operations; and lat_mem_rd measures read latency. 1MB was used as the data size in for bw_mem; for lat_mem_rd a stride (step size in bytes) of 128 bytes was used with a 1MB data size.

     

     Test Name Units Linux PSP 04.06.00.07 Android Devkit 3.0.1
    bw_mem-rd-1MB MB/s 244.82 245.78
    bw_mem-wr-1MB MB/s 871.46 862.48
    bw_mem-rdwr-1MB MB/s 197.8 197.42
    bw_mem-cp-1MB MB/s 179.55 176.2
    lat_mem_rd-stride128-sz50 ns 4.21 4.211
    lat_mem_rd-stride128-sz31k ns 4.19 4.206
    lat_mem_rd-stride128-sz62k ns 12.7 12.759
    lat_mem_rd-stride128-sz125k ns 16.18 16.261
    lat_mem_rd-stride128-sz250k ns 57.68 66.353
    lat_mem_rd-stride128-sz500k ns 219.24 221.942
    lat_mem_rd-stride128-sz1000k ns 264.16

    266.059

     

  • 0 in reply to Jeff Culverhouse
    TI__Intellectual 1930 points

    hi Jeff,

    Our key customer compared DDR read speed between AM3352 300MHz(16 bit 266MHz DDR2) and ATMEL SAM9263(ARM926EJ-S) 200Mhz(32 bit 100Mhz SDRAM) , and found that there is no performance improvement as they think there should be at least 2X improvement. Could you please help to provide an analysis on the root cause of this bottlenect? Below is the test date:

                                   AM3352 @300MHZ        SAM9263@200MHZ
                                 16BIT 266MHZ DDR2     32BIT 100MHZ SDRAM
    bw_mem 1M rd          181.42 MB/s                    194.36 MB/s
    bw_mem 1M bzero     595.86 MB/s                    164.84 MB/s

    1) SAM9263(ARM926EJ-S) 200MHZ，32BIT SDRAM，100MHZ，Linux2.6 by bw_mem：
    runLmDDRBandwidth.sh
    BANDWIDTH MEASUREMENTS

    (MB)  (MB/s)
    ---------------
    bw_mem 1M rd
    1.05 194.36
    bw_mem 1M rdwr
    1.05 91.31
    bw_mem 1M cp
    1.05 142.90
    bw_mem 1M frd
    1.05 139.38
    bw_mem 1M fcp
    1.05 86.03
    bw_mem 1M bzero
    1.05 164.84
    bw_mem 1M bcopy
    1.05 92.32

    2). AM3352 300MHZ，VDDCORE = 1.1V，VDDMPU = 1.2V, 16BIT DDR2 RAM，266MHZ，Linux3.2  by bw_mem：
    root@am335x-evm:~# runLmDDRBandwidth.sh
    BANDWIDTH MEASUREMENTS
     
    (MB)  (MB/s)
    ---------------
    bw_mem 1M rd
    1.00 181.42
    bw_mem 1M rdwr
    1.00 152.58
    bw_mem 1M cp
    1.00 149.68
    bw_mem 1M frd
    1.00 157.70
    bw_mem 1M fcp
    1.00 136.41
    bw_mem 1M bzero
    1.00 595.86
    bw_mem 1M bcopy
    1.00 199.92