Hi Shaohua, On Thu, Aug 06, 2009 at 09:58:55AM +0800, Shaohua Li wrote: > Hi, > > On Wed, Aug 05, 2009 at 10:25:53PM +0800, Gautham R Shenoy wrote: > > In this patch-series, we propose to extend the CPU-Hotplug infrastructure > > and allow the system administrator to choose the desired state the CPU > > should > > go to when it is offlined. We think this approach addresses the concerns > > about > > determinism as well as transparency, since CPU-Hotplug already provides > > notification mechanism which the userspace can listen to for any change > > in the configuration and correspondingly readjust any previously set > > cpu-affinities. > Peter dislikes any approach (including cpuhotplug) which breaks userspace > policy, > even userspace can get a notification.
I think Peter's problem was more to do with the kernel offlining the CPUs behind the scenes, right ? We don't do that in this patch series. The option to offline the CPUs is very much with the admin. The patch-series only provides the interface that helps the admin choose the state the CPU must reside in when it goes offline. > > > Also, approaches such as [1] can make use of this > > extended infrastructure instead of putting the CPU to an arbitrary C-state > > when it is offlined, thereby providing the system administrator a rope to > > hang > > himself with should he feel the need to do so. > I didn't see the reason why administrator needs to know which state offline > cpu > should stay. Don't know about powerpc side, but in x86 side, it appears > deepest > C-state is already preferred. We can still provide a sane default value based on what states are available and what the BIOS limits us to. Thus we can still use the idle-state-offline patch that Venki posted sometime ago, right ? > > Thanks, > Shaohua -- Thanks and Regards gautham _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
