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From: riel@redhat.com
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, mtosatti@redhat.com,
	mingo@kernel.org, ak@linux.intel.com, oleg@redhat.com,
	masami.hiramatsu.pt@hitachi.com, fweisbec@gmail.com,
	paulmck@linux.vnet.ibm.com, lcapitulino@redhat.com,
	pbonzini@redhat.com
Subject: [PATCH 0/4] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest
Date: Thu,  5 Feb 2015 11:35:30 -0500	[thread overview]
Message-ID: <1423154134-17391-1-git-send-email-riel@redhat.com> (raw)

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.


             reply	other threads:[~2015-02-05 16:36 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-05 16:35 riel [this message]
2015-02-05 16:35 ` [PATCH 1/4] rcu,nohz: add state parameter to context_tracking_user_enter/exit riel
2015-02-05 16:35 ` [PATCH 2/4] rcu,nohz: run vtime_user_enter/exit only when state == IN_USER riel
2015-02-05 16:35 ` [PATCH 3/4] nohz,kvm: export context_tracking_user_enter/exit riel
2015-02-05 16:35 ` [PATCH 4/4] kvm,rcu: use RCU extended quiescent state when running KVM guest riel
2015-02-05 16:44   ` Christian Borntraeger
2015-02-05 16:52     ` Rik van Riel
2015-02-05 17:50       ` Paul E. McKenney
2015-02-05 18:09         ` Rik van Riel
2015-02-05 18:56           ` Paul E. McKenney
2015-02-05 18:59             ` Rik van Riel
2015-02-05 19:02             ` Rik van Riel
2015-02-05 19:27               ` Paul E. McKenney
2015-02-05 20:19                 ` Rik van Riel

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