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* [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest
@ 2015-02-05 20:23 riel
  2015-02-05 20:23 ` [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit riel
                   ` (6 more replies)
  0 siblings, 7 replies; 34+ messages in thread
From: riel @ 2015-02-05 20:23 UTC (permalink / raw)
  To: kvm
  Cc: borntraeger, linux-kernel, mtosatti, mingo, ak, oleg,
	masami.hiramatsu.pt, fweisbec, paulmck, lcapitulino, pbonzini

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 user space code.

This patch series extends that code a little bit to make it usable
to track KVM guest space, too.

I tested the code by booting a KVM guest with idle=poll, on a system
with NOHZ_FULL enabled on most CPUs, and a VCPU thread bound to a
CPU. In a 10 second interval, rcuos/N threads on other CPUs got woken
up several times, while the rcuos thread on the CPU running the bound
and alwasy running VCPU thread never got woken up once.

Thanks to Christian Borntraeger and Paul McKenney for reviewing the
first version of this patch series, and helping optimize patch 4/5.


^ permalink raw reply	[flat|nested] 34+ messages in thread

end of thread, other threads:[~2015-02-09 15:42 UTC | newest]

Thread overview: 34+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-02-05 20:23 [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest riel
2015-02-05 20:23 ` [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit riel
2015-02-05 23:55   ` Paul E. McKenney
2015-02-06 10:15     ` Paolo Bonzini
2015-02-06 13:41       ` Paul E. McKenney
2015-02-06 17:22   ` Frederic Weisbecker
2015-02-06 18:20     ` Rik van Riel
2015-02-06 18:23       ` Frederic Weisbecker
2015-02-06 18:51         ` Rik van Riel
2015-02-06 23:15           ` Frederic Weisbecker
2015-02-07  3:53             ` Rik van Riel
2015-02-07  6:34               ` Paul E. McKenney
2015-02-07  7:14                 ` Paul E. McKenney
2015-02-07  8:30                   ` Frederic Weisbecker
2015-02-07 11:29                     ` Rik van Riel
2015-02-07 20:06                     ` Paul E. McKenney
2015-02-09 15:42                       ` Rik van Riel
2015-02-05 20:23 ` [PATCH 2/5] rcu,nohz: run vtime_user_enter/exit only when state == IN_USER riel
2015-02-05 20:23 ` [PATCH 3/5] nohz,kvm: export context_tracking_user_enter/exit riel
2015-02-05 23:55   ` Paul E. McKenney
2015-02-05 20:23 ` [PATCH 4/5] kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest riel
2015-02-05 23:56   ` Paul E. McKenney
2015-02-06 18:01   ` Frederic Weisbecker
2015-02-06 23:24   ` Frederic Weisbecker
2015-02-05 20:23 ` [PATCH 5/5] nohz: add stub context_tracking_is_enabled riel
2015-02-05 23:56   ` Paul E. McKenney
2015-02-06 13:46 ` [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest Frederic Weisbecker
2015-02-06 13:50   ` Paolo Bonzini
2015-02-06 16:19     ` Paul E. McKenney
2015-02-06 18:09     ` Frederic Weisbecker
2015-02-06 14:56   ` Rik van Riel
2015-02-06 18:05     ` Frederic Weisbecker
2015-02-06 15:00 ` Christian Borntraeger
2015-02-06 18:20   ` Frederic Weisbecker

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