Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Fri, Feb 06, 2015 at 04:00:27PM +0100, Christian Borntraeger wrote: > Am 05.02.2015 um 21:23 schrieb r...@redhat.com: > > When running a KVM guest on a system with NOHZ_FULL enabled, and the > > KVM guest running with idle=poll mode, we still get wakeups of the > > rcuos/N threads. > > > >

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Fri, Feb 06, 2015 at 02:50:44PM +0100, Paolo Bonzini wrote: > > > On 06/02/2015 14:46, Frederic Weisbecker wrote: > > > When running a KVM guest on a system with NOHZ_FULL enabled > > > > I just need to clarify the motivation first, does the above situation > > really happen? Ok some distros

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Fri, Feb 06, 2015 at 09:56:43AM -0500, Rik van Riel wrote: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA1 > > On 02/06/2015 08:46 AM, Frederic Weisbecker wrote: > > On Thu, Feb 05, 2015 at 03:23:47PM -0500, r...@redhat.com wrote: > >> When running a KVM guest on a system with NOHZ_FULL

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Paul E. McKenney
On Fri, Feb 06, 2015 at 02:50:44PM +0100, Paolo Bonzini wrote: > > > On 06/02/2015 14:46, Frederic Weisbecker wrote: > > > When running a KVM guest on a system with NOHZ_FULL enabled > > > > I just need to clarify the motivation first, does the above situation > > really happen? Ok some distros

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Christian Borntraeger
Am 05.02.2015 um 21:23 schrieb r...@redhat.com: > When running a KVM guest on a system with NOHZ_FULL enabled, and the > KVM guest running with idle=poll mode, we still get wakeups of the > rcuos/N threads. > > This problem has already been solved for user space by telling the > RCU subsystem

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Rik van Riel
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 02/06/2015 08:46 AM, Frederic Weisbecker wrote: > On Thu, Feb 05, 2015 at 03:23:47PM -0500, r...@redhat.com wrote: >> When running a KVM guest on a system with NOHZ_FULL enabled > > I just need to clarify the motivation first, does the above >

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Paolo Bonzini
On 06/02/2015 14:46, Frederic Weisbecker wrote: > > When running a KVM guest on a system with NOHZ_FULL enabled > > I just need to clarify the motivation first, does the above situation > really happen? Ok some distros enable NOHZ_FULL to let the user stop > the tick in userspace. So most of

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Thu, Feb 05, 2015 at 03:23:47PM -0500, r...@redhat.com wrote: > When running a KVM guest on a system with NOHZ_FULL enabled I just need to clarify the motivation first, does the above situation really happen? Ok some distros enable NOHZ_FULL to let the user stop the tick in userspace. So most

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Paolo Bonzini
On 06/02/2015 14:46, Frederic Weisbecker wrote: When running a KVM guest on a system with NOHZ_FULL enabled I just need to clarify the motivation first, does the above situation really happen? Ok some distros enable NOHZ_FULL to let the user stop the tick in userspace. So most of the

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Thu, Feb 05, 2015 at 03:23:47PM -0500, r...@redhat.com wrote: When running a KVM guest on a system with NOHZ_FULL enabled I just need to clarify the motivation first, does the above situation really happen? Ok some distros enable NOHZ_FULL to let the user stop the tick in userspace. So most

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Rik van Riel
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 02/06/2015 08:46 AM, Frederic Weisbecker wrote: On Thu, Feb 05, 2015 at 03:23:47PM -0500, r...@redhat.com wrote: When running a KVM guest on a system with NOHZ_FULL enabled I just need to clarify the motivation first, does the above situation

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Christian Borntraeger
Am 05.02.2015 um 21:23 schrieb r...@redhat.com: When running a KVM guest on a system with NOHZ_FULL enabled, and the KVM guest running with idle=poll mode, we still get wakeups of the rcuos/N threads. This problem has already been solved for user space by telling the RCU subsystem that the

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Fri, Feb 06, 2015 at 09:56:43AM -0500, Rik van Riel wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 02/06/2015 08:46 AM, Frederic Weisbecker wrote: On Thu, Feb 05, 2015 at 03:23:47PM -0500, r...@redhat.com wrote: When running a KVM guest on a system with NOHZ_FULL enabled

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Fri, Feb 06, 2015 at 02:50:44PM +0100, Paolo Bonzini wrote: On 06/02/2015 14:46, Frederic Weisbecker wrote: When running a KVM guest on a system with NOHZ_FULL enabled I just need to clarify the motivation first, does the above situation really happen? Ok some distros enable

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Paul E. McKenney
On Fri, Feb 06, 2015 at 02:50:44PM +0100, Paolo Bonzini wrote: On 06/02/2015 14:46, Frederic Weisbecker wrote: When running a KVM guest on a system with NOHZ_FULL enabled I just need to clarify the motivation first, does the above situation really happen? Ok some distros enable

Re: [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-06 Thread Frederic Weisbecker
On Fri, Feb 06, 2015 at 04:00:27PM +0100, Christian Borntraeger wrote: Am 05.02.2015 um 21:23 schrieb r...@redhat.com: When running a KVM guest on a system with NOHZ_FULL enabled, and the KVM guest running with idle=poll mode, we still get wakeups of the rcuos/N threads. This problem

[PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-05 Thread riel
When running a KVM guest on a system with NOHZ_FULL enabled, and the KVM guest running with idle=poll mode, we still get wakeups of the rcuos/N threads. This problem has already been solved for user space by telling the RCU subsystem that the CPU is in an extended quiescent state while running

[PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest

2015-02-05 Thread riel
When running a KVM guest on a system with NOHZ_FULL enabled, and the KVM guest running with idle=poll mode, we still get wakeups of the rcuos/N threads. This problem has already been solved for user space by telling the RCU subsystem that the CPU is in an extended quiescent state while running