Commit bd9f0686 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Paul E. McKenney
Browse files

rcu: Repurpose no-CBs event tracing to future-GP events 



Dyntick-idle CPUs need to be able to pre-announce their need for grace
periods.  This can be done using something similar to the mechanism used
by no-CB CPUs to announce their need for grace periods.  This commit
moves in this direction by renaming the no-CBs grace-period event tracing
to suit the new future-grace-period needs.

Signed-off-by: default avatarPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent b92db6cb

include/trace/events/rcu.h

+8 −8
Original line number Diff line number Diff line
@@ -72,10 +72,10 @@ TRACE_EVENT(rcu_grace_period, 
);



/*

 * Tracepoint for no-callbacks grace-period events.  The caller should

 * pull the data from the rcu_node structure, other than rcuname, which

 * comes from the rcu_state structure, and event, which is one of the

 * following:

 * Tracepoint for future grace-period events, including those for no-callbacks

 * CPUs.  The caller should pull the data from the rcu_node structure,

 * other than rcuname, which comes from the rcu_state structure, and event,

 * which is one of the following:

 *

 * "Startleaf": Request a nocb grace period based on leaf-node data.

 * "Startedleaf": Leaf-node start proved sufficient.
@@ -87,7 +87,7 @@ TRACE_EVENT(rcu_grace_period, 
 * "Cleanup": Clean up rcu_node structure after previous GP.

 * "CleanupMore": Clean up, and another no-CB GP is needed.

 */

TRACE_EVENT(rcu_nocb_grace_period,

TRACE_EVENT(rcu_future_grace_period,



	TP_PROTO(char *rcuname, unsigned long gpnum, unsigned long completed,

		 unsigned long c, u8 level, int grplo, int grphi,
@@ -653,7 +653,7 @@ TRACE_EVENT(rcu_barrier, 
#define trace_rcu_grace_period(rcuname, gpnum, gpevent) do { } while (0)

#define trace_rcu_grace_period_init(rcuname, gpnum, level, grplo, grphi, \

				    qsmask) do { } while (0)

#define trace_rcu_nocb_grace_period(rcuname, gpnum, completed, c, \

#define trace_rcu_future_grace_period(rcuname, gpnum, completed, c, \

				      level, grplo, grphi, event) \

				      do { } while (0)

#define trace_rcu_preempt_task(rcuname, pid, gpnum) do { } while (0)

kernel/rcutree_plugin.h

+32 −30
Original line number Diff line number Diff line
@@ -2034,7 +2034,7 @@ static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) 
	wake_up_all(&rnp->nocb_gp_wq[c & 0x1]);

	rnp->n_nocb_gp_requests[c & 0x1] = 0;

	needmore = rnp->n_nocb_gp_requests[(c + 1) & 0x1];

	trace_rcu_nocb_grace_period(rsp->name, rnp->gpnum, rnp->completed,

	trace_rcu_future_grace_period(rsp->name, rnp->gpnum, rnp->completed,

				      c, rnp->level, rnp->grplo, rnp->grphi,

				      needmore ? "CleanupMore" : "Cleanup");

	return needmore;
@@ -2183,9 +2183,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 


	/* Count our request for a grace period. */

	rnp->n_nocb_gp_requests[c & 0x1]++;

	trace_rcu_nocb_grace_period(rdp->rsp->name, rnp->gpnum, rnp->completed,

				    c, rnp->level, rnp->grplo, rnp->grphi,

				    "Startleaf");

	trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,

				      rnp->completed, c, rnp->level,

				      rnp->grplo, rnp->grphi, "Startleaf");



	if (rnp->gpnum != rnp->completed) {
@@ -2194,9 +2194,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
		 * is in progress, so we are done.  When this grace

		 * period ends, our request will be acted upon.

		 */

		trace_rcu_nocb_grace_period(rdp->rsp->name,

					    rnp->gpnum, rnp->completed, c,

					    rnp->level, rnp->grplo, rnp->grphi,

		trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,

					      rnp->completed, c, rnp->level,

					      rnp->grplo, rnp->grphi,

					      "Startedleaf");

		raw_spin_unlock_irqrestore(&rnp->lock, flags);
@@ -2209,8 +2209,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
		if (rnp != rnp_root)

			raw_spin_lock(&rnp_root->lock); /* irqs disabled. */

		if (rnp_root->gpnum != rnp_root->completed) {

			trace_rcu_nocb_grace_period(rdp->rsp->name,

						    rnp->gpnum, rnp->completed,

			trace_rcu_future_grace_period(rdp->rsp->name,

						      rnp->gpnum,

						      rnp->completed,

						      c, rnp->level,

						      rnp->grplo, rnp->grphi,

						      "Startedleafroot");
@@ -2229,8 +2230,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
			c = rnp_root->completed + 1;

			rnp->n_nocb_gp_requests[c & 0x1]++;

			rnp_root->n_nocb_gp_requests[c & 0x1]++;

			trace_rcu_nocb_grace_period(rdp->rsp->name,

						    rnp->gpnum, rnp->completed,

			trace_rcu_future_grace_period(rdp->rsp->name,

						      rnp->gpnum,

						      rnp->completed,

						      c, rnp->level,

						      rnp->grplo, rnp->grphi,

						      "Startedroot");
@@ -2249,9 +2251,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
	 * Wait for the grace period.  Do so interruptibly to avoid messing

	 * up the load average.

	 */

	trace_rcu_nocb_grace_period(rdp->rsp->name, rnp->gpnum, rnp->completed,

				    c, rnp->level, rnp->grplo, rnp->grphi,

				    "StartWait");

	trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,

				      rnp->completed, c, rnp->level,

				      rnp->grplo, rnp->grphi, "StartWait");

	for (;;) {

		wait_event_interruptible(

			rnp->nocb_gp_wq[c & 0x1],
@@ -2259,14 +2261,14 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
		if (likely(d))

			break;

		flush_signals(current);

		trace_rcu_nocb_grace_period(rdp->rsp->name,

		trace_rcu_future_grace_period(rdp->rsp->name,

					      rnp->gpnum, rnp->completed, c,

					    rnp->level, rnp->grplo, rnp->grphi,

					    "ResumeWait");

					      rnp->level, rnp->grplo,

					      rnp->grphi, "ResumeWait");

	}

	trace_rcu_nocb_grace_period(rdp->rsp->name, rnp->gpnum, rnp->completed,

				    c, rnp->level, rnp->grplo, rnp->grphi,

				    "EndWait");

	trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,

				      rnp->completed, c, rnp->level,

				      rnp->grplo, rnp->grphi, "EndWait");

	smp_mb(); /* Ensure that CB invocation happens after GP end. */

}

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