Hello,
I'm using kernel 4.8 on i.MX53.
My device uses 3 USB serial chipsets (ftdi) to collect data.
CPU usage on my previous kernel 2.6.38 was just 45~50%.
But on kernel 4.8.15 it exceeds 80%.
So I profiled using perf and top.
Most of the CPU resource is used on work_queue function in the USB driver.
Anybody has good ideas to reduce cpu usage?
Thank you.
1. perf report.
11.92% QSGRenderThread [kernel.kallsyms] [k] __do_softirq
8.27% QSGRenderThread [kernel.kallsyms] [k] __usb_hcd_giveback_urb
6.94% swapper [kernel.kallsyms] [k] __do_softirq
6.37% swapper [kernel.kallsyms] [k] __usb_hcd_giveback_urb
3.97% DisplayService [kernel.kallsyms] [k] __do_softirq
2.02% swapper [kernel.kallsyms] [k] cpuidle_enter_state
2. Top result. --> in kernel 2.6 below 3 kworker was under 1%
Tasks: 108 total, 2 running, 106 sleeping, 0 stopped, 0 zombie
%Cpu(s): 48.9 us, 21.2 sy, 0.0 ni, 17.2 id, 0.0 wa, 0.0 hi, 12.8 si, 0.0 st
9.5% kworker/u2:2
8.0% kworker/u2:3
2.1% kworker/u2:0
