Re: [PATCH v3 08/12] sched: move cfs task on a CPU with higher capacity

On 10 July 2014 13:18, Peter Zijlstra peterz@infradead.org wrote:

On Mon, Jun 30, 2014 at 06:05:39PM +0200, Vincent Guittot wrote:

...

•         /*
  

•          * If the CPUs share their cache and the src_cpu's capacity is
  

•          * reduced because of other sched_class or IRQs, we trig an
  

•          * active balance to move the task
  

•          */
  

•         if ((sd->flags & SD_SHARE_PKG_RESOURCES)
  

•          && ((capacity_orig_of(src_cpu) * 100) > (capacity_of(src_cpu) *
  

•                                                 sd->imbalance_pct)))
                  return 1;
  

Why is this tied to shared caches?

It's just to limit the change of the policy to a level that can have benefit without performance regression. I'm not sure that we can do that at any level without risk