Re: 4.2: CONFIG_NO_HZ_FULL_ALL effectively disabling non-boot CPUs

2015-10-11 Thread Frederic Weisbecker
On Sat, Oct 10, 2015 at 12:24:39PM -0700, Paul E. McKenney wrote: > On Sat, Oct 10, 2015 at 10:14:25PM +0300, Meelis Roos wrote: > > Short summary: turning on CONFIG_NO_HZ_FULL_ALL seems to disable all > > non-boot CPUs for scheduler. > > > > A couple of days ago I noticed that make -j8 on a 4-co

Re: 4.2: CONFIG_NO_HZ_FULL_ALL effectively disabling non-boot CPUs

2015-10-11 Thread Meelis Roos
> > Short summary: turning on CONFIG_NO_HZ_FULL_ALL seems to disable all > > non-boot CPUs for scheduler. [...] > This is expected and intended behavior. The whole point of > CONFIG_NO_HZ_FULL_ALL is to keep everything off of the non-boot CPUs > that is not explicitly placed there. Without CON

Re: 4.2: CONFIG_NO_HZ_FULL_ALL effectively disabling non-boot CPUs

2015-10-10 Thread Paul E. McKenney
On Sat, Oct 10, 2015 at 10:14:25PM +0300, Meelis Roos wrote: > Short summary: turning on CONFIG_NO_HZ_FULL_ALL seems to disable all > non-boot CPUs for scheduler. > > A couple of days ago I noticed that make -j8 on a 4-core i5 is very slow > (with 4.3.0-rc4+git). Looking at top ('1' for per-cpu

4.2: CONFIG_NO_HZ_FULL_ALL effectively disabling non-boot CPUs

2015-10-10 Thread Meelis Roos
Short summary: turning on CONFIG_NO_HZ_FULL_ALL seems to disable all non-boot CPUs for scheduler. A couple of days ago I noticed that make -j8 on a 4-core i5 is very slow (with 4.3.0-rc4+git). Looking at top ('1' for per-cpu states), only first CPU is loaded and 3 other CPUs are 100% idle. This