On Sun, 2016-04-10 at 17:39 +0200, Mike Galbraith wrote: > On Sat, 2016-04-09 at 14:31 +0200, Rafael J. Wysocki wrote: > > > > On Sat, Apr 9, 2016 at 1:07 PM, Peter Zijlstra <pet...@infradead.or > > g> > > wrote: > > > > > > On Fri, Apr 08, 2016 at 10:59:59PM +0200, Rafael J. Wysocki > > > wrote: > > > > > > > > On Friday, April 08, 2016 08:50:54 AM Mike Galbraith wrote: > > > > > > > > > > On Fri, 2016-04-08 at 08:45 +0200, Peter Zijlstra wrote: > > > > > > > > > > > > > > > > > Cute, I thought you used governor=performance for your > > > > > > runs? > > > > > I do, and those numbers are with it thus set. > > > > Well, this is a trade-off. > > > > > > > > 4.5 introduced a power regression here so this one goes back to > > > > the previous > > > > state of things. > > > Just for my elucidation; how can gov=performance have a 'power' > > > regression? > > Because of what is used as the "default" idle state most of the > > time. > > > > C1 was used before 4.5 and that changed to polling in 4.5. > Should the default idle state not then be governor dependent? When I > set gov=performance, I'm expecting box to go just as fast as it can > go > without melting. Does polling risk CPU -> lava conversion?
Current CPUs can only have some cores run at full speed (turbo mode) if other cores are idling and/or running at lower speeds. It may be time to stop pretending that gov=performance actually results in better performance on current CPUs, since it may inhibit entire levels of turbo mode. -- All Rights Reversed.
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