On Fri, 10 Nov 2017 11:14:51 +0000 Bruce Richardson <bruce.richard...@intel.com> wrote:
> On Fri, Nov 10, 2017 at 11:42:56AM +0100, Daniel Bristot de Oliveira wrote: > > > > > > On 11/10/2017 11:14 AM, Ananyev, Konstantin wrote: > > > Agree with Adrian here - the patch doesn't fix the problem in any case, > > > > I would agree with you if it were possible to assume one can fully > > isolate a CPU on Linux... but it is not... > > > > This: > > https://lwn.net/Articles/659490/ > > > > is still an open issue, and the reason why it is an open issue is the > > kernel threads that need to run on every CPU, mainly when using the > > PREEMPT_RT, which turns almost everything on threads. > > > > > while introducing an unnecessary slowdown in testpmd iofwd mode. > > > Please think up some other approach. > > > > The other approach is to increase the priority of all other threads that > > run on the isolate CPU. But that is not a good idea at all, as the other > > threads might preempt the busy-loop thread at the worst possible moment. > > > > Using the knowledge of the thread about when it is the best time to give > > a chance for other threads to run would be a smarter decision. > > > I don't like having this in the main loop either, and to echo others I > wouldn't have thought that testpmd was actually used as anything other > than a testing app. That's why we're patching it. We want to be aware of the implications. If it's not good for testpmd, it may not be good for production either.
