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Subject[PATCH tip/core/rcu 10/14] rcu: Repurpose no-CBs event tracing to future-GP events
Date
From: "Paul E. McKenney" <paul.mckenney@linaro.org>

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: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/trace/events/rcu.h | 16 +++++-----
kernel/rcutree_plugin.h | 62 ++++++++++++++++++++++---------------------
2 files changed, 40 insertions(+), 38 deletions(-)

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index ef0bf31..0dc0177 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -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,
@@ -645,9 +645,9 @@ 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, \
- level, grplo, grphi, event) \
- do { } while (0)
+#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)
#define trace_rcu_unlock_preempted_task(rcuname, gpnum, pid) do { } while (0)
#define trace_rcu_quiescent_state_report(rcuname, gpnum, mask, qsmask, level, \
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 9371bdd..d09acdf 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2073,9 +2073,9 @@ 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,
- c, rnp->level, rnp->grplo, rnp->grphi,
- needmore ? "CleanupMore" : "Cleanup");
+ trace_rcu_future_grace_period(rsp->name, rnp->gpnum, rnp->completed,
+ c, rnp->level, rnp->grplo, rnp->grphi,
+ needmore ? "CleanupMore" : "Cleanup");
return needmore;
}

@@ -2222,9 +2222,9 @@ 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) {

@@ -2233,10 +2233,10 @@ 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,
- "Startedleaf");
+ 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);

} else {
@@ -2248,11 +2248,12 @@ 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,
- c, rnp->level,
- rnp->grplo, rnp->grphi,
- "Startedleafroot");
+ trace_rcu_future_grace_period(rdp->rsp->name,
+ rnp->gpnum,
+ rnp->completed,
+ c, rnp->level,
+ rnp->grplo, rnp->grphi,
+ "Startedleafroot");
raw_spin_unlock(&rnp_root->lock); /* irqs disabled. */
} else {

@@ -2268,11 +2269,12 @@ 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,
- c, rnp->level,
- rnp->grplo, rnp->grphi,
- "Startedroot");
+ trace_rcu_future_grace_period(rdp->rsp->name,
+ rnp->gpnum,
+ rnp->completed,
+ c, rnp->level,
+ rnp->grplo, rnp->grphi,
+ "Startedroot");
local_save_flags(flags1);
rcu_start_gp(rdp->rsp, flags1); /* Rlses ->lock. */
}
@@ -2288,9 +2290,9 @@ 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],
@@ -2298,14 +2300,14 @@ 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,
- rnp->gpnum, rnp->completed, c,
- rnp->level, rnp->grplo, rnp->grphi,
- "ResumeWait");
+ trace_rcu_future_grace_period(rdp->rsp->name,
+ rnp->gpnum, rnp->completed, c,
+ 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. */
}

--
1.7.8


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