rcu: Add tracing for RCU_FAST_NO_HZ (433cdddc) · Commits · 戴 / test

include/trace/events/rcu.h

+37 −0

Original line number	Diff line number	Diff line
		@@ -274,6 +274,42 @@ TRACE_EVENT(rcu_dyntick,
		__entry->oldnesting, __entry->newnesting)
		);

		/*
		* Tracepoint for RCU preparation for idle, the goal being to get RCU
		* processing done so that the current CPU can shut off its scheduling
		* clock and enter dyntick-idle mode. One way to accomplish this is
		* to drain all RCU callbacks from this CPU, and the other is to have
		* done everything RCU requires for the current grace period. In this
		* latter case, the CPU will be awakened at the end of the current grace
		* period in order to process the remainder of its callbacks.
		*
		* These tracepoints take a string as argument:
		*
		* "No callbacks": Nothing to do, no callbacks on this CPU.
		* "In holdoff": Nothing to do, holding off after unsuccessful attempt.
		* "Dyntick with callbacks": Callbacks remain, but RCU doesn't need CPU.
		* "Begin holdoff": Attempt failed, don't retry until next jiffy.
		* "More callbacks": Still more callbacks, try again to clear them out.
		* "Callbacks drained": All callbacks processed, off to dyntick idle!
		* "CPU awakened at GP end":
		*/
		TRACE_EVENT(rcu_prep_idle,

		TP_PROTO(char *reason),

		TP_ARGS(reason),

		TP_STRUCT__entry(
		__field(char *, reason)
		),

		TP_fast_assign(
		__entry->reason = reason;
		),

		TP_printk("%s", __entry->reason)
		);

		/*
		* Tracepoint for the registration of a single RCU callback function.
		* The first argument is the type of RCU, the second argument is
		@@ -482,6 +518,7 @@ TRACE_EVENT(rcu_torture_read,
		#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)

kernel/rcutree_plugin.h

+15 −3

Original line number	Diff line number	Diff line
		@@ -2031,10 +2031,13 @@ static void rcu_prepare_for_idle(int cpu)
		/* If no callbacks or in the holdoff period, enter dyntick-idle. */
		if (!rcu_cpu_has_callbacks(cpu)) {
		per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
		trace_rcu_prep_idle("No callbacks");
		return;
		}
		if (per_cpu(rcu_dyntick_holdoff, cpu) == jiffies)
		if (per_cpu(rcu_dyntick_holdoff, cpu) == jiffies) {
		trace_rcu_prep_idle("In holdoff");
		return;
		}

		/* Check and update the rcu_dyntick_drain sequencing. */
		if (per_cpu(rcu_dyntick_drain, cpu) <= 0) {
		@@ -2044,9 +2047,11 @@ static void rcu_prepare_for_idle(int cpu)
		/* We have hit the limit, so time to give up. */
		per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
		if (!rcu_pending(cpu)) {
		trace_rcu_prep_idle("Dyntick with callbacks");
		per_cpu(rcu_awake_at_gp_end, cpu) = 1;
		return; /* Nothing to do immediately. */
		}
		trace_rcu_prep_idle("Begin holdoff");
		invoke_rcu_core(); /* Force the CPU out of dyntick-idle. */
		return;
		}
		@@ -2073,9 +2078,15 @@ static void rcu_prepare_for_idle(int cpu)
		c = c \|\| per_cpu(rcu_bh_data, cpu).nxtlist;
		}

		/* If RCU callbacks are still pending, RCU still needs this CPU. */
		if (c)
		/*
		* If RCU callbacks are still pending, RCU still needs this CPU.
		* So try forcing the callbacks through the grace period.
		*/
		if (c) {
		trace_rcu_prep_idle("More callbacks");
		invoke_rcu_core();
		} else
		trace_rcu_prep_idle("Callbacks drained");
		}

		/*
		@@ -2085,6 +2096,7 @@ static void rcu_prepare_for_idle(int cpu)
		*/
		static void rcu_wake_cpu(void *unused)
		{
		trace_rcu_prep_idle("CPU awakened at GP end");
		invoke_rcu_core();
		}

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