RAM memory bandwidth

Discussion of your EDM baseboard, your add-on boards or other peripherals for your wandboard.

RAM memory bandwidth

Postby Loic » Wed Oct 19, 2016 7:08 am


I am working with Wandboard DL with Linux 4.0.4 configured for SMP.

We have 4 DDR3 chips of 128Mb at 396MHz and a bus width of 32bits.
128M * 16 DDR3-1600 11-11-11

I think the maximum bandwidth is:
Channel Width ( bits/transfert) * speed (Transfert/second)
= 32 * (396Mhz *2 )
= 3168 MB/sec

I make some measures with dd.

I used the following commands:
mkdir /tmp/mytmpfs
mount -t tmpfs -o size=1024M tmpfs /tmp/mytmpfs
dd if=/dev/zero of=file.bin bs=1024k count=500

Measures show that the bandwidth for file access on the ram disk is 214.1MB/s.
There is a factor of 14.79 between calculate maximum bandwidth and measured bandwidth. (3168/214.1)

Do you think that’s correct bandwidth?
With maximum bandwidth of 3168Mb, which useful bandwidth can we expected?

Thanks in advance for your help

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Joined: Tue Oct 18, 2016 2:41 pm

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