eMMC 5.1 - slow sequential write

Hello,

I’m testing eMMC 5.1 performance and I’m noticed slow sequential write on it.

In spec emmc 5.1 will have sequential write about 125MB/s and sequential read about 250MB/s

I got results (using dd):

time sh -c “dd if=/dev/zero of=/home/file bs=4k count=200000 && sync”
wrtie : 35MB/s

echo 3 > /proc/sys/vm/drop_caches
time sh -c “dd if=/home/file of=/dev/zero bs=4k count=200000”
read: 235MB/s

anybody can confirm it?

Hi Santyago,

Before running the I/O performance test, have you set CPU freq and EMC freq to max speed or desired speed.
Also be sure to enable all CPU online.

Thanks

Hi, Thanks for reply!

I’m set CPU & EMC to max freq, all cpu are online.

Hi Santyago, apologies if this seems redundant, but just to clarify, the results you posted originally were with CPU and EMC frequencies set to maximum?

Results from first post are on max frequencies :)

Hi Santyago,

By further investigation, with less data size, comes less speed.
Have you tried to test with other DD_BLKSIZES, such as 512K?
Supposed the result should be closed the emmc 5.1 spec with maximum speed of sequential write about 125MB/s and sequential read about 250MB/s

Thanks

I got max sequential write ~60MB/s (4K blk size) on maximum CPU & EMC frequencies.