AM6548: Test SD card read/write speed

Hi Eric,

Numbers from TI EVM can be found here
http://software-dl.ti.com/processor-sdk-linux/esd/docs/latest/linux/Release_Specific_Performance_Guide.html#id9

I will get back to you on the procedure used to measure them.

Regards,
Vishal

Hi Vishal,

Thanks for the performance info.

I have correct the cmd I test and found there is a file created on SD card. However, there is still no speed info.

Please refer to below screen shot.

Please let me know if you have the procedure.

Thanks.

Eric

Hi,

The dd tool in our SDK file system is from busybox and this version does not show speed info.
You can see the same behavior on your PC (output below from PC)

$ busybox dd if=/dev/zero of=./temp bs=4k count=4k
4096+0 records in
4096+0 records out

$ dd if=/dev/zero of=./temp bs=4k count=4k
4096+0 records in
4096+0 records out
16777216 bytes (17 MB) copied, 0.0144137 s, 1.2 GB/s

We use ltp-ddt to measure throughput on our SDK.
At a very high level, we use dd tool to create test files and measure the time taken to read and write files.

Regards,
Vishal

Hi Vishal,

So, we need to use ltp-ddt but not dd command. Right?

I tired to use it on AM65xx EVM board.

However, when I follow the procedure in README-DDT Section6&7, I have some questions.

1. Please let me know which Toolchain to choose, I use Linaro Toolchain arm-linux-gnueabihf currently. I don't know if it is suitable for AM65xx.

2. Then I go to build steps "make autotools". I met some errors as below.

    If I go to the wrong directory?

3. Do you have detail procedure for us?

Thanks.

Eric

Hi Eric,

dd can also be used, but you may have to use a different dd and not the busybox version which does not give the additional info on speed.
I was highlighting the numbers published in TI release notes and the procedure used.

Regards,
Vishal

Hi VIshal,

Could you let us know which is different dd not busybox version?

We still want to measure the speed but not the numbers in release note.

Thanks.

Eric

Hi Eric,

You can try cross-compiling this project for arm64 to get regular dd
https://git.savannah.gnu.org/gitweb/?p=coreutils.git

Regards,
Vishal

Hi Vishal,

Finally, I use "time dd" to do the test. However, I am confusing the result.

From the below screen shot, the speed will faster than 28MB/s. But I use a Class10 8GB sd card.

Compare to your result, it seems unreasonable.

Can you provide some comment? 

Thanks.

Eric

Hi,

We do the below command before measuring throughput
echo 3 > /proc/sys/vm/drop_caches

Regards,
Vishal

Also, if you want regular dd via coreutils package, you can do the below command to get the coreutils package via network on your board.

# opkg install coreutils

Hi Vishal,

I use dd by adding a "conv" flag to test, below is the result.

"time sudo dd if=/dev/zero of=/home/root/temp bs=1M count=2 conv=fsync"  

From your report, it should be 20MB/sec when testing with 1M file, but my result is almost half yours.

Is that related to mmc setting?

I found the setting in dtsi of mmc is mmc-hs200-1_8v. Is that the same setting with your test?

Thanks.

Eric

Hi Eric,

What type of SD card are you using? Also, the kernel boot log would say what speed mode the SD card enumerated.
The TI SDK release note mentions "Sandisk 8GB SDHC UHS Card" was used for measurements.

Regards,
Vishal

Hi Vishal,

We use Phison SHDC 8G Class 10.

[ 3.905842] mmc1: new high speed SDHC card at address 0007
[ 3.916660] mmcblk1: mmc1:0007 SD08G 7.42 GiB
[ 3.922362] mmcblk1: p1 p2

Any possible reason about this?

Eric

Hi Eric,

The test was done with same settings as in SDK release with the procedure I shared with you earlier.

The property 'mmc-hs200-1_8v' you were talking about in your previous response corresponds to sdhci0 - eMMC.
SD card slot is connected to SD sdhci1. 

Regards,
Vishal

Also, below points are mentioned in the release notes...
http://software-dl.ti.com/processor-sdk-linux/esd/docs/latest/linux/Release_Specific_Performance_Guide.html#id8

The performance numbers were captured using the following:

• SanDisk 8GB SDHC UHS Memory Card
• Partition was mounted with async option