Re: Context switch latency in tickless isolated CPU

On Sun, Aug 21, 2016 at 07:26:04PM +0800, GeHao Kang wrote:

On Fri, Aug 19, 2016 at 8:34 PM, Peter Zijlstra [off-list ref] wrote:

quoted

Why are you wanting to use nohz_full if you do syscalls?

We hope to reduce the overhead of the tick while the real time
applications run,
and these applications might do some syscalls to operate the I/O devices like
EtherCAT.

If latency is all you care about, one approach is to map the device
registers into userspace and do the I/O without assistance from the
kernel.

Alternatively, use in-memory mailbox/queuing techniques to hand the
I/O off to some other thread.

							Thanx, Paul