Hi Sai, On Tue, May 12, 2015 at 11:07:26PM +0100, Sai Gurrappadi wrote: > > On 05/12/2015 12:38 PM, Morten Rasmussen wrote: > > Test results for ARM TC2 (2xA15+3xA7) with cpufreq enabled: > > > > sysbench: Single task running for 3 seconds. > > rt-app [4]: mp3 playback use-case model > > rt-app [4]: 5 ~[6,13,19,25,31,38,44,50]% periodic (2ms) tasks > > > > Note: % is relative to the capacity of the fastest cpu at the highest > > frequency, i.e. the more busy ones do not fit on little cpus. > > > > A newer version of rt-app was used which supports a better but slightly > > different way of modelling the periodic tasks. Numbers are therefore > > _not_ comparable to the RFCv3 numbers. > > > > Average numbers for 20 runs per test (ARM TC2). > > > > Energy Mainline EAS noEAS > > > > sysbench 100 251* 227* > > > > rt-app mp3 100 63 111 > > > > rt-app 6% 100 42 102 > > rt-app 13% 100 58 101 > > rt-app 19% 100 87 101 > > rt-app 25% 100 94 104 > > rt-app 31% 100 93 104 > > rt-app 38% 100 114 117 > > rt-app 44% 100 115 118 > > rt-app 50% 100 125 126 > > Hi Morten, > > What is noEAS? From the numbers, noEAS != Mainline?
Sorry, that should have been more clear. Mainline: tip/sched/core (not really mainline yet...) EAS: tip/sched/core + RFCv4 + EAS enabled. noEAS: tip/sched/core + RFCv4 + EAS disabled. The main differences between plain tip/sched/core and EAS disabled is that PELT is frequency invariant which affects the decisions in period/idle/nohz_idle balance. > Maybe also have some perf numbers to show that perf is in fact preserved > while lowering power. Couldn't agree more. Energy numbers on their own do not say much. I hinted at the sysbench performance in the (trimmed) text further down. The increase in energy for EAS is due to doing more work (higher performance). The rt-app runs with task utilization in the lower end should deliver the same level of performance as none of the cpus are fully utilized. The little cpus have a capacity of 43% each. At the higher end I would expect performance to be different. EAS tries its best to put heavier tasks on the big cpus where mainline may choose a different task distribution hence performance is likely to be different like it is for sysbench. A performance metric for rt-app is under discussion but not there yet. We will work on getting that sorted as the next thing so we can see any performance impact. Thanks, Morten -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
