Re: [PATCH v6 1/3] perf/core: use rb trees for pinned/flexible groups

[Alexey Budankov <alexey.budankov@linux.intel.com>]

On 07.08.2017 19:57, Peter Zijlstra wrote:
> On Mon, Aug 07, 2017 at 07:27:30PM +0300, Alexey Budankov wrote:
>> On 07.08.2017 18:55, Peter Zijlstra wrote:
> 
>>> In the extreme, if you construct your program such that you'll never get
>>> hit by the tick (this used to be a popular measure to hide yourself from
>>> time accounting)
>>
>> Well, some weird thing for me. Never run longer than one tick? 
>> I could imaging some I/O bound code that would fast serve some short 
>> messages, all the other time waiting for incoming requests.
>> Not sure if CPU events monitoring is helpful in this case.
> 
> Like I said, in extreme. Typically its less weird.> 
> Another example is scheduling a very constrained counter/group along
> with a bunch of simple events such that the group will only succeed to
> schedule when its the first. In this case it will get only 1/nr_events
> time with RR, as opposed to the other/simple events that will get
> nr_counters/nr_events time.
> 
> By making it runtime based, the constrained thing will more often be
> head of list and acquire equal total runtime to the other events.

I see and what could be the triggering condition for runtime based scheduling 
of groups as an alternative to hrtimer signal?

>