On Fri, May 12, 2017 at 11:07:48AM -0500, Christoph Lameter wrote:

On Fri, 12 May 2017, Marcelo Tosatti wrote:

quoted

In our case, vmstat updates are very rare (CPU is dominated by DPDK).

What is the OS doing on the cores that DPDK runs on? I mean we here can
clean a processor of all activities and are able to run for a long time
without any interruptions.

Why would you still let the OS do things on that processor? If activities
by the OS are required then the existing NOHZ setup already minimizes
latency to a short burst (and Chris Metcalf's work improves on that).


What exactly is the issue you are seeing and want to address? I think we
have similar aims and as far as I know the current situation is already
good enough for what you may need. You may just not be aware of how to
configure this.

I want to disable vmstat worker thread completly from an isolated CPU.
Because it adds overhead to a latency target, target which 
the lower the better.

I doubt that doing inline updates will do much good compared to what we
already have and what the dataplan mode can do.

Can the dataplan mode disable vmstat worker thread completly on a given
CPU?