Re: [PATCH 5/5] sched/rt: Optimize find_lowest_rq() to select a cache hot cpu

Steven Rostedt
2015-01-29T17:17:47Z

On Fri, 30 Jan 2015 00:42:47 +0800
Xunlei Pang <pang.xunlei@linaro.org> wrote:

> I think the responsiveness is the most important feature for RT tasks,
> so I think:
> response latency > cache > SMT in significance.

Unfortunately, sometimes cache affects response latency.

>
> I was wondering if we can take the cpuidle state into account like
> current find_idlest_cpu() for CFS?
> cpupri_find() can be easily modified to indicate the CPUPRI_IDLE case,
> then we can select
> an optimal idle cpu to improve RT tasks' responsiveness. For other
> cases(mostly non-idle cpu),

Even if that idle cpu happens to be on another NUMA node?

-- Steve

> I think we can rely on the existent sched_domain iteraction to select
> a cache-hot cpu without
> caring too much about SMT.