On Thu, 30 Sep 2021, John Ogness wrote: > On 2021-09-30, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > >> With hackbench, the system is sufficiently busy to avoid the going > >> into idle. > > > > Not just that. cyclictest's usage of /dev/cpu_dma_latency has the side > > effect that it may disable some of the PM stuff in the system. > > So your system appears good but then when cyclictest is gone, the > > numbers go up. > > > > Maybe we should drop that so we observe a system without altering its > > behaviour? > > +1 > > Developers wanting to explicitly cause this behavior can use --latency= > to enable it. Having it on as a default is misleading. > > John Ogness > If you pass "--laptop" to cyclictest then it won't use the trick of writing to /dev/cpu_dma_latency in order to save battery power. It doesn't matter whether you are really running on a laptop or not. John Kacur
