imx6s vs imx6q memory bandwidth difference

denniedegroot — Tue, 24 Apr 2018 10:59:38 GMT

Hello,

Currently I am developing on 2 custom boards with a identical layout. The difference is the used processor.

One board has a iMX6S and the other board a iMX6Q processor. Both boards have the same DDR configuration so the chips (MT41K128M16JT-125:K) and layout (32-bit) are identical. The DDR on the boards are independently calibrated.

However when running "bw_mem" (part of lmbench) I get very different results as the table below shows.

The 'bzero' test for instance is 6x slower on the Quadcore then on the Solo.

Command	iMX6 Solo	iMX6 Quadcore
bw_mem -P 1 -N 4 128M rd	1417.69	1318.39
bw_mem -P 1 -N 4 128M wr	467.34	373.44
bw_mem -P 1 -N 4 128M rdwr	486.82	397.27
bw_mem -P 1 -N 4 128M cp	460.50	342.82
bw_mem -P 1 -N 4 128M fwr	2178.06	370.24
bw_mem -P 1 -N 4 128M frd	1158.55	622.61
bw_mem -P 1 -N 4 128M fcp	768.31	317.41
bw_mem -P 1 -N 4 128M bzero	2175.32	339.56
bw_mem -P 1 -N 4 128M bcopy	770.06	355.44

Does anyone know why there is such a big difference between the Solo and Quadcore with identical DDR configuration?

Re: imx6s vs imx6q memory bandwidth difference

igorpadykov — Tue, 24 Apr 2018 23:11:21 GMT

Hi Dennie

one can use profile tool for memory bandwidth analysis

About MMDC Profiling Tool for i.MX6

Also difference may be caused by different NIC-301 settings

described in Chapter 45 Network Interconnect Bus System (NIC-301)

i.MX6DQ Reference Manual.

Best regards
igor
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imx6s vs imx6q memory bandwidth difference

Re: imx6s vs imx6q memory bandwidth difference