we are running the linux-fslc kernel 4.9 on imx28 alongside a filesystem built with Yocto (Morty). It seems that any amount of work is 'too much' for the cpu. for example, under idle conditions, top shows 'us' loading of around 15% and 'sy' loading of 3%. As soon as you run any application the loading goes up the roof hitting almost 70% - 80% on trivial tasks.
Earlier, we found that having kernel debugging was making a significant impact which is now taken care of by disabling all kernel debugging esp. the kernel lock validator. But even with that change the system doesn't look like it is running a 200MIPS CPU at all. very sluggish!!
Some kernel tracing reveals no apparent bottlenecks (e.g scheduler looks fine so do interrupts etc). It seems that the processor it taking longer to execute instructions. note the clocks seem running at the right speed and kernel reports bogomips of 226.09
Has anyone had a similar experience with imx28? any ideas?