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https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-02 16:44:10 +08:00
7cb9249900
The current implementation of RCU_FAST_NO_HZ prevents CPUs from entering dyntick-idle state if they have RCU callbacks pending. Unfortunately, this has the side-effect of often preventing them from entering this state, especially if at least one other CPU is not in dyntick-idle state. However, the resulting per-tick wakeup is wasteful in many cases: if the CPU has already fully responded to the current RCU grace period, there will be nothing for it to do until this grace period ends, which will frequently take several jiffies. This commit therefore permits a CPU that has done everything that the current grace period has asked of it (rcu_pending() == 0) even if it still as RCU callbacks pending. However, such a CPU posts a timer to wake it up several jiffies later (6 jiffies, based on experience with grace-period lengths). This wakeup is required to handle situations that can result in all CPUs being in dyntick-idle mode, thus failing to ever complete the current grace period. If a CPU wakes up before the timer goes off, then it cancels that timer, thus avoiding spurious wakeups. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
536 lines
15 KiB
C
536 lines
15 KiB
C
#undef TRACE_SYSTEM
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#define TRACE_SYSTEM rcu
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#if !defined(_TRACE_RCU_H) || defined(TRACE_HEADER_MULTI_READ)
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#define _TRACE_RCU_H
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#include <linux/tracepoint.h>
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/*
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* Tracepoint for start/end markers used for utilization calculations.
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* By convention, the string is of the following forms:
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*
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* "Start <activity>" -- Mark the start of the specified activity,
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* such as "context switch". Nesting is permitted.
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* "End <activity>" -- Mark the end of the specified activity.
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*
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* An "@" character within "<activity>" is a comment character: Data
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* reduction scripts will ignore the "@" and the remainder of the line.
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*/
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TRACE_EVENT(rcu_utilization,
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TP_PROTO(char *s),
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TP_ARGS(s),
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TP_STRUCT__entry(
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__field(char *, s)
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),
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TP_fast_assign(
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__entry->s = s;
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),
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TP_printk("%s", __entry->s)
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);
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#ifdef CONFIG_RCU_TRACE
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#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
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/*
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* Tracepoint for grace-period events: starting and ending a grace
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* period ("start" and "end", respectively), a CPU noting the start
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* of a new grace period or the end of an old grace period ("cpustart"
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* and "cpuend", respectively), a CPU passing through a quiescent
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* state ("cpuqs"), a CPU coming online or going offline ("cpuonl"
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* and "cpuofl", respectively), and a CPU being kicked for being too
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* long in dyntick-idle mode ("kick").
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*/
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TRACE_EVENT(rcu_grace_period,
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TP_PROTO(char *rcuname, unsigned long gpnum, char *gpevent),
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TP_ARGS(rcuname, gpnum, gpevent),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(unsigned long, gpnum)
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__field(char *, gpevent)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->gpnum = gpnum;
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__entry->gpevent = gpevent;
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),
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TP_printk("%s %lu %s",
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__entry->rcuname, __entry->gpnum, __entry->gpevent)
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);
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/*
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* Tracepoint for grace-period-initialization events. These are
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* distinguished by the type of RCU, the new grace-period number, the
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* rcu_node structure level, the starting and ending CPU covered by the
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* rcu_node structure, and the mask of CPUs that will be waited for.
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* All but the type of RCU are extracted from the rcu_node structure.
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*/
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TRACE_EVENT(rcu_grace_period_init,
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TP_PROTO(char *rcuname, unsigned long gpnum, u8 level,
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int grplo, int grphi, unsigned long qsmask),
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TP_ARGS(rcuname, gpnum, level, grplo, grphi, qsmask),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(unsigned long, gpnum)
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__field(u8, level)
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__field(int, grplo)
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__field(int, grphi)
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__field(unsigned long, qsmask)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->gpnum = gpnum;
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__entry->level = level;
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__entry->grplo = grplo;
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__entry->grphi = grphi;
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__entry->qsmask = qsmask;
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),
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TP_printk("%s %lu %u %d %d %lx",
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__entry->rcuname, __entry->gpnum, __entry->level,
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__entry->grplo, __entry->grphi, __entry->qsmask)
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);
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/*
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* Tracepoint for tasks blocking within preemptible-RCU read-side
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* critical sections. Track the type of RCU (which one day might
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* include SRCU), the grace-period number that the task is blocking
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* (the current or the next), and the task's PID.
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*/
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TRACE_EVENT(rcu_preempt_task,
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TP_PROTO(char *rcuname, int pid, unsigned long gpnum),
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TP_ARGS(rcuname, pid, gpnum),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(unsigned long, gpnum)
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__field(int, pid)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->gpnum = gpnum;
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__entry->pid = pid;
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),
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TP_printk("%s %lu %d",
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__entry->rcuname, __entry->gpnum, __entry->pid)
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);
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/*
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* Tracepoint for tasks that blocked within a given preemptible-RCU
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* read-side critical section exiting that critical section. Track the
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* type of RCU (which one day might include SRCU) and the task's PID.
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*/
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TRACE_EVENT(rcu_unlock_preempted_task,
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TP_PROTO(char *rcuname, unsigned long gpnum, int pid),
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TP_ARGS(rcuname, gpnum, pid),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(unsigned long, gpnum)
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__field(int, pid)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->gpnum = gpnum;
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__entry->pid = pid;
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),
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TP_printk("%s %lu %d", __entry->rcuname, __entry->gpnum, __entry->pid)
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);
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/*
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* Tracepoint for quiescent-state-reporting events. These are
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* distinguished by the type of RCU, the grace-period number, the
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* mask of quiescent lower-level entities, the rcu_node structure level,
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* the starting and ending CPU covered by the rcu_node structure, and
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* whether there are any blocked tasks blocking the current grace period.
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* All but the type of RCU are extracted from the rcu_node structure.
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*/
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TRACE_EVENT(rcu_quiescent_state_report,
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TP_PROTO(char *rcuname, unsigned long gpnum,
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unsigned long mask, unsigned long qsmask,
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u8 level, int grplo, int grphi, int gp_tasks),
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TP_ARGS(rcuname, gpnum, mask, qsmask, level, grplo, grphi, gp_tasks),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(unsigned long, gpnum)
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__field(unsigned long, mask)
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__field(unsigned long, qsmask)
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__field(u8, level)
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__field(int, grplo)
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__field(int, grphi)
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__field(u8, gp_tasks)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->gpnum = gpnum;
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__entry->mask = mask;
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__entry->qsmask = qsmask;
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__entry->level = level;
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__entry->grplo = grplo;
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__entry->grphi = grphi;
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__entry->gp_tasks = gp_tasks;
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),
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TP_printk("%s %lu %lx>%lx %u %d %d %u",
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__entry->rcuname, __entry->gpnum,
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__entry->mask, __entry->qsmask, __entry->level,
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__entry->grplo, __entry->grphi, __entry->gp_tasks)
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);
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/*
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* Tracepoint for quiescent states detected by force_quiescent_state().
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* These trace events include the type of RCU, the grace-period number
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* that was blocked by the CPU, the CPU itself, and the type of quiescent
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* state, which can be "dti" for dyntick-idle mode, "ofl" for CPU offline,
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* or "kick" when kicking a CPU that has been in dyntick-idle mode for
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* too long.
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*/
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TRACE_EVENT(rcu_fqs,
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TP_PROTO(char *rcuname, unsigned long gpnum, int cpu, char *qsevent),
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TP_ARGS(rcuname, gpnum, cpu, qsevent),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(unsigned long, gpnum)
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__field(int, cpu)
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__field(char *, qsevent)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->gpnum = gpnum;
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__entry->cpu = cpu;
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__entry->qsevent = qsevent;
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),
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TP_printk("%s %lu %d %s",
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__entry->rcuname, __entry->gpnum,
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__entry->cpu, __entry->qsevent)
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);
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#endif /* #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) */
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/*
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* Tracepoint for dyntick-idle entry/exit events. These take a string
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* as argument: "Start" for entering dyntick-idle mode, "End" for
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* leaving it, "--=" for events moving towards idle, and "++=" for events
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* moving away from idle. "Error on entry: not idle task" and "Error on
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* exit: not idle task" indicate that a non-idle task is erroneously
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* toying with the idle loop.
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*
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* These events also take a pair of numbers, which indicate the nesting
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* depth before and after the event of interest. Note that task-related
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* events use the upper bits of each number, while interrupt-related
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* events use the lower bits.
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*/
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TRACE_EVENT(rcu_dyntick,
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TP_PROTO(char *polarity, long long oldnesting, long long newnesting),
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TP_ARGS(polarity, oldnesting, newnesting),
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TP_STRUCT__entry(
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__field(char *, polarity)
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__field(long long, oldnesting)
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__field(long long, newnesting)
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),
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TP_fast_assign(
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__entry->polarity = polarity;
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__entry->oldnesting = oldnesting;
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__entry->newnesting = newnesting;
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),
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TP_printk("%s %llx %llx", __entry->polarity,
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__entry->oldnesting, __entry->newnesting)
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);
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/*
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* Tracepoint for RCU preparation for idle, the goal being to get RCU
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* processing done so that the current CPU can shut off its scheduling
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* clock and enter dyntick-idle mode. One way to accomplish this is
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* to drain all RCU callbacks from this CPU, and the other is to have
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* done everything RCU requires for the current grace period. In this
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* latter case, the CPU will be awakened at the end of the current grace
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* period in order to process the remainder of its callbacks.
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*
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* These tracepoints take a string as argument:
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*
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* "No callbacks": Nothing to do, no callbacks on this CPU.
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* "In holdoff": Nothing to do, holding off after unsuccessful attempt.
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* "Begin holdoff": Attempt failed, don't retry until next jiffy.
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* "Dyntick with callbacks": Entering dyntick-idle despite callbacks.
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* "More callbacks": Still more callbacks, try again to clear them out.
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* "Callbacks drained": All callbacks processed, off to dyntick idle!
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* "Timer": Timer fired to cause CPU to continue processing callbacks.
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*/
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TRACE_EVENT(rcu_prep_idle,
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TP_PROTO(char *reason),
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TP_ARGS(reason),
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TP_STRUCT__entry(
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__field(char *, reason)
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),
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TP_fast_assign(
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__entry->reason = reason;
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),
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TP_printk("%s", __entry->reason)
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);
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/*
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* Tracepoint for the registration of a single RCU callback function.
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* The first argument is the type of RCU, the second argument is
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* a pointer to the RCU callback itself, and the third element is the
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* new RCU callback queue length for the current CPU.
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*/
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TRACE_EVENT(rcu_callback,
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TP_PROTO(char *rcuname, struct rcu_head *rhp, long qlen),
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TP_ARGS(rcuname, rhp, qlen),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(void *, rhp)
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__field(void *, func)
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__field(long, qlen)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->rhp = rhp;
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__entry->func = rhp->func;
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__entry->qlen = qlen;
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),
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TP_printk("%s rhp=%p func=%pf %ld",
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__entry->rcuname, __entry->rhp, __entry->func, __entry->qlen)
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);
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/*
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* Tracepoint for the registration of a single RCU callback of the special
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* kfree() form. The first argument is the RCU type, the second argument
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* is a pointer to the RCU callback, the third argument is the offset
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* of the callback within the enclosing RCU-protected data structure,
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* and the fourth argument is the new RCU callback queue length for the
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* current CPU.
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*/
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TRACE_EVENT(rcu_kfree_callback,
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TP_PROTO(char *rcuname, struct rcu_head *rhp, unsigned long offset,
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long qlen),
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TP_ARGS(rcuname, rhp, offset, qlen),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(void *, rhp)
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__field(unsigned long, offset)
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__field(long, qlen)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->rhp = rhp;
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__entry->offset = offset;
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__entry->qlen = qlen;
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),
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TP_printk("%s rhp=%p func=%ld %ld",
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__entry->rcuname, __entry->rhp, __entry->offset,
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__entry->qlen)
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);
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/*
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* Tracepoint for marking the beginning rcu_do_batch, performed to start
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* RCU callback invocation. The first argument is the RCU flavor,
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* the second is the total number of callbacks (including those that
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* are not yet ready to be invoked), and the third argument is the
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* current RCU-callback batch limit.
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*/
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TRACE_EVENT(rcu_batch_start,
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TP_PROTO(char *rcuname, long qlen, int blimit),
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TP_ARGS(rcuname, qlen, blimit),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(long, qlen)
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__field(int, blimit)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->qlen = qlen;
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__entry->blimit = blimit;
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),
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TP_printk("%s CBs=%ld bl=%d",
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__entry->rcuname, __entry->qlen, __entry->blimit)
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);
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/*
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* Tracepoint for the invocation of a single RCU callback function.
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* The first argument is the type of RCU, and the second argument is
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* a pointer to the RCU callback itself.
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*/
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TRACE_EVENT(rcu_invoke_callback,
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TP_PROTO(char *rcuname, struct rcu_head *rhp),
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TP_ARGS(rcuname, rhp),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(void *, rhp)
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__field(void *, func)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->rhp = rhp;
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__entry->func = rhp->func;
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),
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TP_printk("%s rhp=%p func=%pf",
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__entry->rcuname, __entry->rhp, __entry->func)
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);
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/*
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* Tracepoint for the invocation of a single RCU callback of the special
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* kfree() form. The first argument is the RCU flavor, the second
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* argument is a pointer to the RCU callback, and the third argument
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* is the offset of the callback within the enclosing RCU-protected
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* data structure.
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*/
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TRACE_EVENT(rcu_invoke_kfree_callback,
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TP_PROTO(char *rcuname, struct rcu_head *rhp, unsigned long offset),
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TP_ARGS(rcuname, rhp, offset),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(void *, rhp)
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__field(unsigned long, offset)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->rhp = rhp;
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__entry->offset = offset;
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),
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TP_printk("%s rhp=%p func=%ld",
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__entry->rcuname, __entry->rhp, __entry->offset)
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);
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/*
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* Tracepoint for exiting rcu_do_batch after RCU callbacks have been
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* invoked. The first argument is the name of the RCU flavor and
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* the second argument is number of callbacks actually invoked.
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*/
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TRACE_EVENT(rcu_batch_end,
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TP_PROTO(char *rcuname, int callbacks_invoked),
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TP_ARGS(rcuname, callbacks_invoked),
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TP_STRUCT__entry(
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__field(char *, rcuname)
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__field(int, callbacks_invoked)
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),
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TP_fast_assign(
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__entry->rcuname = rcuname;
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__entry->callbacks_invoked = callbacks_invoked;
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),
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TP_printk("%s CBs-invoked=%d",
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__entry->rcuname, __entry->callbacks_invoked)
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);
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/*
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* Tracepoint for rcutorture readers. The first argument is the name
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* of the RCU flavor from rcutorture's viewpoint and the second argument
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* is the callback address.
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*/
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TRACE_EVENT(rcu_torture_read,
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TP_PROTO(char *rcutorturename, struct rcu_head *rhp),
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TP_ARGS(rcutorturename, rhp),
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TP_STRUCT__entry(
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__field(char *, rcutorturename)
|
|
__field(struct rcu_head *, rhp)
|
|
),
|
|
|
|
TP_fast_assign(
|
|
__entry->rcutorturename = rcutorturename;
|
|
__entry->rhp = rhp;
|
|
),
|
|
|
|
TP_printk("%s torture read %p",
|
|
__entry->rcutorturename, __entry->rhp)
|
|
);
|
|
|
|
#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_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_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_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) do { } while (0)
|
|
#define trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
|
|
|
|
#endif /* #else #ifdef CONFIG_RCU_TRACE */
|
|
|
|
#endif /* _TRACE_RCU_H */
|
|
|
|
/* This part must be outside protection */
|
|
#include <trace/define_trace.h>
|