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LMBench on ARM Microprocessors

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What is LMBench

LMBench is an opensource benchmark suite available under the GNU General Public License. You can download LMBench here:

Test set up

  • AM37x rev C
  • OMAP EVM Main Board Rev G
  • Cortex-A8 clock speed of 600MHz
  • L3 clock rate of 200MHz.
  • Linux version - 2.6.32 (PSP03.00.01.06)
  • Compiler version - (gcc version 4.3.3 (Sourcery G++ Lite 2009q1-203)

Memory Latency

The following results come from the LMBench test lat_mem_read with stride=128. This test can be helpful to understand the latency of data reads from L1, L2 and memory. Smaller block reads can fit entirely into L1, so they should have less latency than larger block reads.

Memory Latency Results

Block tranfer size ns clock  cycles
512 Bytes 5.059 3.0354
2K Bytes 5.059 3.0354
4K Bytes 5.059 3.0354
16K Bytes 5.034 3.0204
32K Bytes 5.028 3.0168
48K Bytes 12.842 7.7052
64K Bytes 15.239 9.1434
128K Bytes 19.436 11.6616
192K Bytes 20.362 12.2172
256K Bytes 37.598 22.5588
384K Bytes 113.683 68.2098
512K Bytes 140.427 84.2562
768K Bytes 155.576 93.3456
1M Bytes 161.576 96.9456

Read Memory Bandwidth

The following results come from the LMBench test bw_mem. This test is using the exact same setup as the previous test however, it is run with two different Cortex-A8 clock speeds - 600MHz and 1 GHz. All the reads and writes of this test are performed by the Cortex-A8.

Memory Latency Results

Operation Clock speed - 600MHz Clock speed -1GHz
(rd) read 1MByte - 32 bit stride - 4 bytes at a time 386.43 MB/s 412.71 MB/s
(rdwr) read/write 1 MByte - 32 bit stride - 4 bytes at a time 274.8 MB/s 310.61 MB/s
(cp) copy 1 MByte - 32 bit stride - 4 bytes at a time 328.03 MB/s 345.01 MB/s
(fcp) copy 1 MByte no stride - 4 bytes at a time 279.77 MB/s 329.95 MB/s
bcopy copy 1 MByte - 1 byte at a time 266.42 MB/s 321.96 MB/s