Re: [PATCH v5] sched: Avoid unnecessary work in reweight_entity

[Srivatsa Vaddagiri]

* Michael Wang <wangyun@xxxxxxxxxxxxxxxxxx> [2012-02-25 21:56:18]:

> Hi, Peter
> 
> I have collected more testing data, here is the test results:
> 
> Machine:	ThinkPad T420
> OS:		Ubuntu 11.10
> Benchmark:	time make -j14 (build kernel)

Is that benchmark run in root (cpu) cgroup? If so, reweight_entity() should not
kick in at all.

static void update_cfs_shares(struct cfs_rq *cfs_rq)
{

        ..

        if (!se || throttled_hierarchy(cfs_rq))
                return;

        ..

	reweight_entity();
}

If you want to stress reweight_entity() create several (cpu) cgroups
and launch workload like kernbench in each of them ..

- vatsa

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