On Thu, 2013-02-21 at 22:40 +0800, Alex Shi wrote: > > The name is a secondary issue, first you need to explain why you > think > > nr_running is a useful metric at all. > > > > You can have a high nr_running and a low utilization (a burst of > > wakeups, each waking a process that'll instantly go to sleep again), > or > > low nr_running and high utilization (a single process cpu bound > > process). > > It is true in periodic balance. But in fork/exec/waking timing, the > incoming processes usually need to do something before sleep again.
You'd be surprised, there's a fair number of workloads that have negligible runtime on wakeup. > I use nr_running to measure how the group busy, due to 3 reasons: > 1, the current performance policy doesn't use utilization too. We were planning to fix that now that its available. > 2, the power policy don't care load weight. Then its broken, it should very much still care about weight. > 3, I tested some benchmarks, kbuild/tbench/hackbench/aim7 etc, some > benchmark results looks clear bad when use utilization. if my memory > right, the hackbench/aim7 both looks bad. I had tried many ways to > engage utilization into this balance, like use utilization only, or > use > utilization * nr_running etc. but still can not find a way to recover > the lose. But with nr_running, the performance seems doesn't lose much > with power policy. You're failing to explain why utilization performs bad and you don't explain why nr_running is better. That things work simply isn't good enough, you have to have at least a general idea (but much preferable a very good idea) _why_ things work. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
