Commit 19fdd98b authored Feb 10, 2015 by Rik van Riel Committed by Frederic Weisbecker Mar 09, 2015

context_tracking: Run vtime_user_enter/exit only when state == CONTEXT_USER



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.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will deacon <will.deacon@arm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

parent a3a9c7df

kernel/context_tracking.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -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.
		*/
		if (state == CONTEXT_USER) {
		trace_user_enter(0);
		vtime_user_enter(current);
		}
		rcu_user_enter();
		}
		/*
		@@ -143,9 +145,11 @@ void context_tracking_exit(enum ctx_state state)
		* RCU core about that (ie: we may need the tick again).
		*/
		rcu_user_exit();
		if (state == CONTEXT_USER) {
		vtime_user_exit(current);
		trace_user_exit(0);
		}
		}
		__this_cpu_write(context_tracking.state, CONTEXT_KERNEL);
		}
		local_irq_restore(flags);