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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-01-07 02:11:30 +0400
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-02-21 21:03:25 +0400
commit486e259340fc4c60474f2c14703e3b3634bb58ca (patch)
tree70a58702194588fa0773463523f72c682785d040 /include/trace
parent0bb7b59d6e2b8440cd7097097dd4bbfc4d76ed07 (diff)
downloadlinux-486e259340fc4c60474f2c14703e3b3634bb58ca.tar.xz
rcu: Avoid waking up CPUs having only kfree_rcu() callbacks
When CONFIG_RCU_FAST_NO_HZ is enabled, RCU will allow a given CPU to enter dyntick-idle mode even if it still has RCU callbacks queued. RCU avoids system hangs in this case by scheduling a timer for several jiffies in the future. However, if all of the callbacks on that CPU are from kfree_rcu(), there is no reason to wake the CPU up, as it is not a problem to defer freeing of memory. This commit therefore tracks the number of callbacks on a given CPU that are from kfree_rcu(), and avoids scheduling the timer if all of a given CPU's callbacks are from kfree_rcu(). Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/trace')
-rw-r--r--include/trace/events/rcu.h63
1 files changed, 39 insertions, 24 deletions
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index d2d88bed891b..337099783f37 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -313,19 +313,22 @@ TRACE_EVENT(rcu_prep_idle,
/*
* Tracepoint for the registration of a single RCU callback function.
* The first argument is the type of RCU, the second argument is
- * a pointer to the RCU callback itself, and the third element is the
- * new RCU callback queue length for the current CPU.
+ * a pointer to the RCU callback itself, the third element is the
+ * number of lazy callbacks queued, and the fourth element is the
+ * total number of callbacks queued.
*/
TRACE_EVENT(rcu_callback,
- TP_PROTO(char *rcuname, struct rcu_head *rhp, long qlen),
+ TP_PROTO(char *rcuname, struct rcu_head *rhp, long qlen_lazy,
+ long qlen),
- TP_ARGS(rcuname, rhp, qlen),
+ TP_ARGS(rcuname, rhp, qlen_lazy, qlen),
TP_STRUCT__entry(
__field(char *, rcuname)
__field(void *, rhp)
__field(void *, func)
+ __field(long, qlen_lazy)
__field(long, qlen)
),
@@ -333,11 +336,13 @@ TRACE_EVENT(rcu_callback,
__entry->rcuname = rcuname;
__entry->rhp = rhp;
__entry->func = rhp->func;
+ __entry->qlen_lazy = qlen_lazy;
__entry->qlen = qlen;
),
- TP_printk("%s rhp=%p func=%pf %ld",
- __entry->rcuname, __entry->rhp, __entry->func, __entry->qlen)
+ TP_printk("%s rhp=%p func=%pf %ld/%ld",
+ __entry->rcuname, __entry->rhp, __entry->func,
+ __entry->qlen_lazy, __entry->qlen)
);
/*
@@ -345,20 +350,21 @@ TRACE_EVENT(rcu_callback,
* kfree() form. The first argument is the RCU type, the second argument
* is a pointer to the RCU callback, the third argument is the offset
* of the callback within the enclosing RCU-protected data structure,
- * and the fourth argument is the new RCU callback queue length for the
- * current CPU.
+ * the fourth argument is the number of lazy callbacks queued, and the
+ * fifth argument is the total number of callbacks queued.
*/
TRACE_EVENT(rcu_kfree_callback,
TP_PROTO(char *rcuname, struct rcu_head *rhp, unsigned long offset,
- long qlen),
+ long qlen_lazy, long qlen),
- TP_ARGS(rcuname, rhp, offset, qlen),
+ TP_ARGS(rcuname, rhp, offset, qlen_lazy, qlen),
TP_STRUCT__entry(
__field(char *, rcuname)
__field(void *, rhp)
__field(unsigned long, offset)
+ __field(long, qlen_lazy)
__field(long, qlen)
),
@@ -366,41 +372,45 @@ TRACE_EVENT(rcu_kfree_callback,
__entry->rcuname = rcuname;
__entry->rhp = rhp;
__entry->offset = offset;
+ __entry->qlen_lazy = qlen_lazy;
__entry->qlen = qlen;
),
- TP_printk("%s rhp=%p func=%ld %ld",
+ TP_printk("%s rhp=%p func=%ld %ld/%ld",
__entry->rcuname, __entry->rhp, __entry->offset,
- __entry->qlen)
+ __entry->qlen_lazy, __entry->qlen)
);
/*
* Tracepoint for marking the beginning rcu_do_batch, performed to start
* RCU callback invocation. The first argument is the RCU flavor,
- * the second is the total number of callbacks (including those that
- * are not yet ready to be invoked), and the third argument is the
- * current RCU-callback batch limit.
+ * the second is the number of lazy callbacks queued, the third is
+ * the total number of callbacks queued, and the fourth argument is
+ * the current RCU-callback batch limit.
*/
TRACE_EVENT(rcu_batch_start,
- TP_PROTO(char *rcuname, long qlen, int blimit),
+ TP_PROTO(char *rcuname, long qlen_lazy, long qlen, int blimit),
- TP_ARGS(rcuname, qlen, blimit),
+ TP_ARGS(rcuname, qlen_lazy, qlen, blimit),
TP_STRUCT__entry(
__field(char *, rcuname)
+ __field(long, qlen_lazy)
__field(long, qlen)
__field(int, blimit)
),
TP_fast_assign(
__entry->rcuname = rcuname;
+ __entry->qlen_lazy = qlen_lazy;
__entry->qlen = qlen;
__entry->blimit = blimit;
),
- TP_printk("%s CBs=%ld bl=%d",
- __entry->rcuname, __entry->qlen, __entry->blimit)
+ TP_printk("%s CBs=%ld/%ld bl=%d",
+ __entry->rcuname, __entry->qlen_lazy, __entry->qlen,
+ __entry->blimit)
);
/*
@@ -531,16 +541,21 @@ TRACE_EVENT(rcu_torture_read,
#else /* #ifdef CONFIG_RCU_TRACE */
#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_grace_period_init(rcuname, gpnum, level, grplo, grphi, \
+ qsmask) 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, grplo, grphi, gp_tasks) do { } while (0)
+#define trace_rcu_quiescent_state_report(rcuname, gpnum, mask, qsmask, level, \
+ grplo, grphi, gp_tasks) do { } \
+ while (0)
#define trace_rcu_fqs(rcuname, gpnum, cpu, qsevent) do { } while (0)
#define trace_rcu_dyntick(polarity, oldnesting, newnesting) do { } while (0)
#define trace_rcu_prep_idle(reason) do { } while (0)
-#define trace_rcu_callback(rcuname, rhp, qlen) do { } while (0)
-#define trace_rcu_kfree_callback(rcuname, rhp, offset, qlen) do { } while (0)
-#define trace_rcu_batch_start(rcuname, qlen, blimit) do { } while (0)
+#define trace_rcu_callback(rcuname, rhp, qlen_lazy, qlen) do { } while (0)
+#define trace_rcu_kfree_callback(rcuname, rhp, offset, qlen_lazy, qlen) \
+ do { } while (0)
+#define trace_rcu_batch_start(rcuname, qlen_lazy, qlen, blimit) \
+ do { } while (0)
#define trace_rcu_invoke_callback(rcuname, rhp) do { } while (0)
#define trace_rcu_invoke_kfree_callback(rcuname, rhp, offset) do { } while (0)
#define trace_rcu_batch_end(rcuname, callbacks_invoked, cb, nr, iit, risk) \