rcu: Trace callback acceleration

This commit adds event tracing for callback acceleration to allow better
tracking of callbacks through the system.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index d4f559b1ec3444eada48e8e9e1d8bd85f36da5b6..5678114073b5bef3b999f879d24c2bb90da72e1c 100644 (file)
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -44,8 +44,10 @@ TRACE_EVENT(rcu_utilization,
  * of a new grace period or the end of an old grace period ("cpustart"
  * and "cpuend", respectively), a CPU passing through a quiescent
  * state ("cpuqs"), a CPU coming online or going offline ("cpuonl"
- * and "cpuofl", respectively), and a CPU being kicked for being too
- * long in dyntick-idle mode ("kick").
+ * and "cpuofl", respectively), a CPU being kicked for being too
+ * long in dyntick-idle mode ("kick"), a CPU accelerating its new
+ * callbacks to RCU_NEXT_READY_TAIL ("AccReadyCB"), and a CPU
+ * accelerating its new callbacks to RCU_WAIT_TAIL ("AccWaitCB").
  */
 TRACE_EVENT(rcu_grace_period,
 

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index ac6a75d152ef9001b399c051be0867c0b1dccfd6..e9dce4fa76d82e91851e3a7fc806869f9f086447 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1168,6 +1168,12 @@ static void rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp,
                rdp->nxttail[i] = rdp->nxttail[RCU_NEXT_TAIL];
                rdp->nxtcompleted[i] = c;
        }
+
+       /* Trace depending on how much we were able to accelerate. */
+       if (!*rdp->nxttail[RCU_WAIT_TAIL])
+               trace_rcu_grace_period(rsp->name, rdp->gpnum, "AccWaitCB");
+       else
+               trace_rcu_grace_period(rsp->name, rdp->gpnum, "AccReadyCB");
 }
 
 /*