Performance - usb storage transfer speed

1. Test the write/read speed to/from block device with dd.

test the write speed to block device '/dev/block/mmcblk0p29', which is local emmc.

time dd if=/dev/zero of=/dev/block/mmcblk0p29 bs=8k count=132691 

test the read speed from block device '/dev/block/mmcblk0p29'

time dd of=/dev/zero if=/dev/block/mmcblk0p29 bs=8k count=132691 

if you want to test with usb otg storage like udisk.

'/dev/block/mmcblk0p29' -> '/dev/block/sda'

'/dev/block/mmcblk0p29' -> '/dev/block/vold/...'

2. And  performance cpu before test

cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
cat /sys/devices/system/cpu/cpu1/cpufreq/cpuinfo_max_freq > /sys/devices/system/cpu/cpu1/cpufreq/scaling_min_freq
cat /sys/devices/system/cpu/cpu2/cpufreq/cpuinfo_max_freq > /sys/devices/system/cpu/cpu2/cpufreq/scaling_min_freq
...
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor

echo performance > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor 

3. Check bus clock on runtime - qualcomm platform - usb

3.1 Compare the difference before test and doing the test

> cat /sys/kernel/debug/clk/pcnoc_clk/measure
> cat /sys/kernel/debug/clk/bimc_clk/measure
> cat /sys/kernel/debug/clk/snoc_clk/measure 

3.2 Check chipset clock plan

'MSM89XX CLOCK PLAN'

3.3 Check the config in dtsi

//source code
134static char bus_clkname[USB_NUM_BUS_CLOCKS][20] = {"bimc_clk", "snoc_clk",
135						"pcnoc_clk"};

//improve the bus clock
-qcom,bus-clk-rate = <400000000 200000000 100000000>;
+qcom,bus-clk-rate = <533000000 266000000 133333000>;