Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-14 Thread Peter Zijlstra
On Tue, Jan 14, 2014 at 04:39:54PM +, Morten Rasmussen wrote: > Responsiveness is still very important. It is quite hard to control. CFS > doesn't consider latency. The only way to get the best responsiveness is > to go for best performance which comes at a high cost in energy. The big

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-14 Thread Morten Rasmussen
On Mon, Jan 13, 2014 at 09:07:12PM +, Rafael J. Wysocki wrote: > On Tuesday, January 07, 2014 04:19:39 PM Morten Rasmussen wrote: > > To minimize energy it may sometimes be better to put waking tasks on > > partially loaded cpus instead of powering up more cpus (particularly if > > it implies

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-14 Thread Peter Zijlstra
On Mon, Jan 13, 2014 at 10:07:12PM +0100, Rafael J. Wysocki wrote: > > Currently, the CFS scheduler has no knowledge about frequency scaling. > > Frequency scaling governors generally try to match the frequency to > > the load, which means that the idle time has no absolute meaning. The > >

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-14 Thread Peter Zijlstra
On Mon, Jan 13, 2014 at 10:07:12PM +0100, Rafael J. Wysocki wrote: Currently, the CFS scheduler has no knowledge about frequency scaling. Frequency scaling governors generally try to match the frequency to the load, which means that the idle time has no absolute meaning. The potential

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-14 Thread Morten Rasmussen
On Mon, Jan 13, 2014 at 09:07:12PM +, Rafael J. Wysocki wrote: On Tuesday, January 07, 2014 04:19:39 PM Morten Rasmussen wrote: To minimize energy it may sometimes be better to put waking tasks on partially loaded cpus instead of powering up more cpus (particularly if it implies

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-14 Thread Peter Zijlstra
On Tue, Jan 14, 2014 at 04:39:54PM +, Morten Rasmussen wrote: Responsiveness is still very important. It is quite hard to control. CFS doesn't consider latency. The only way to get the best responsiveness is to go for best performance which comes at a high cost in energy. The big problem

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-13 Thread Rafael J. Wysocki
On Tuesday, January 07, 2014 04:19:39 PM Morten Rasmussen wrote: > To minimize energy it may sometimes be better to put waking tasks on > partially loaded cpus instead of powering up more cpus (particularly if > it implies powering up a new cluster/group of cpus with associated > caches). To make

Re: [3/11] issue 3: No understanding of potential cpu capacity

2014-01-13 Thread Rafael J. Wysocki
On Tuesday, January 07, 2014 04:19:39 PM Morten Rasmussen wrote: To minimize energy it may sometimes be better to put waking tasks on partially loaded cpus instead of powering up more cpus (particularly if it implies powering up a new cluster/group of cpus with associated caches). To make that