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rcu: Repurpose no-CBs event tracing to future-GP events
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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>
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Paul E. McKenney authored and Paul E. McKenney committed Mar 26, 2013
1 parent b92db6c commit bd9f068
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Showing 2 changed files with 40 additions and 38 deletions.
16 changes: 8 additions & 8 deletions include/trace/events/rcu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand All @@ -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,
Expand Down Expand Up @@ -653,9 +653,9 @@ 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, \
Expand Down
62 changes: 32 additions & 30 deletions kernel/rcutree_plugin.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2034,9 +2034,9 @@ 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;
}

Expand Down Expand Up @@ -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) {

Expand All @@ -2194,10 +2194,10 @@ 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 {
Expand All @@ -2209,11 +2209,12 @@ 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 {

Expand All @@ -2229,11 +2230,12 @@ 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. */
}
Expand All @@ -2249,24 +2251,24 @@ 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],
(d = ULONG_CMP_GE(ACCESS_ONCE(rnp->completed), c)));
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. */
}

Expand Down

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