Re: [RFC PATCH 1/3] sched: add sched_policy and it's sysfs interface

[Alex Shi <alex.shi@intel.com>]

On 11/06/2012 11:20 PM, Luming Yu wrote:
> On Tue, Nov 6, 2012 at 8:09 AM, Alex Shi <alex.shi@intel.com> wrote:
>> This patch add the power aware scheduler knob into sysfs:
> 
> The problem is user doesn't know how to use this knob.
> 
> Based on what data, people could select one policy which could be surely
> better than another?
> 
> "Packing small tasks" approach could be better and more intelligent.
> http://thread.gmane.org/gmane.linux.kernel/1348522

It is not conflict with this patchset. :)
> 
> Just some random thoughts, as I didn't have chance to look into the
> details of that patch set yet. But to me, we need to exploit the fact
> that we could automatically bind a group of tasks on minimal set of
> CPUs that can provide sufficient CPU cycles that are comparable to
> a"cpu- run-average" that the task group can get in pure CFS situation
> in a given period, until we see more CPU is needed.Then we probably
> can maintain required CPU power available to the corresponding
> workload, while leaving all other CPUs into power saving mode. The
> problem is historical data suggested pattern could become invalid in
> future, then we need more CPUs in future..I think this is the point we
> need to know before spread or not-spread decision ...if spread would
> not help CPU-run-average ,we don't need waste CPU power..but I don't
> know how hard it could be. But I'm pretty sure sysfs knob is harder.
> :-) /l
> 


-- 
Thanks
    Alex