From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH 3/5] rcu,nohz: run vtime_user_enter/exit only when state == IN_USER Date: Tue, 10 Feb 2015 13:35:59 -0800 Message-ID: <20150210213559.GZ4166@linux.vnet.ibm.com> References: <1423600074-2907-1-git-send-email-riel@redhat.com> <1423600074-2907-4-git-send-email-riel@redhat.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: fweisbec@gmail.com, luto@amacapital.net, will.deacon@arm.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mtosatti@redhat.com, borntraeger@de.ibm.com, lcapitulino@redhat.com, pbonzini@redhat.com To: riel@redhat.com Return-path: Content-Disposition: inline In-Reply-To: <1423600074-2907-4-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, Feb 10, 2015 at 03:27:52PM -0500, riel@redhat.com wrote: > From: Rik van Riel > > Only run vtime_user_enter, vtime_user_exit, and the user enter & exit > trace points when we are entering or exiting user state, respectively. > > The KVM code in guest_enter and guest_exit already take care of calling > vtime_guest_enter and vtime_guest_exit, respectively. > > The RCU code only distinguishes between "idle" and "not idle or kernel". > There should be no need to add an additional (unused) state there. > > Signed-off-by: Rik van Riel Reviewed-by: Paul E. McKenney > --- > kernel/context_tracking.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c > index 38e38aeac8b9..0e4e318d5ea4 100644 > --- a/kernel/context_tracking.c > +++ b/kernel/context_tracking.c > @@ -77,7 +77,6 @@ void context_tracking_enter(enum ctx_state state) > local_irq_save(flags); > if ( __this_cpu_read(context_tracking.state) != state) { > if (__this_cpu_read(context_tracking.active)) { > - trace_user_enter(0); > /* > * At this stage, only low level arch entry code remains and > * then we'll run in userspace. We can assume there won't be > @@ -85,7 +84,10 @@ void context_tracking_enter(enum ctx_state state) > * user_exit() or rcu_irq_enter(). Let's remove RCU's dependency > * on the tick. > */ > - vtime_user_enter(current); > + if (state == IN_USER) { > + trace_user_enter(0); > + vtime_user_enter(current); > + } > rcu_user_enter(); > } > /* > @@ -143,8 +145,10 @@ void context_tracking_exit(enum ctx_state state) > * RCU core about that (ie: we may need the tick again). > */ > rcu_user_exit(); > - vtime_user_exit(current); > - trace_user_exit(0); > + if (state == IN_USER) { > + vtime_user_exit(current); > + trace_user_exit(0); > + } > } > __this_cpu_write(context_tracking.state, IN_KERNEL); > } > -- > 1.9.3 >