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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-05-23 18:47:05 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-07-02 12:33:23 -0700 |
| commit | a83eff0a82a7f3f14fea477fd41e6c082e7fc96a (patch) | |
| tree | 9fb65b061716c622962c42b8318f06fd0d2919cd /kernel/rcutree.c | |
| parent | cf3a9c4842b1e097dbe0854933c471d43dd24f69 (diff) | |
| download | linux-a83eff0a82a7f3f14fea477fd41e6c082e7fc96a.tar.bz2 | |
rcu: Add tracing for _rcu_barrier()
This commit adds event tracing for _rcu_barrier() execution. This
is defined only if RCU_TRACE=y.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 6bb5d562253f..dda43d826504 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -2260,6 +2260,17 @@ static int rcu_cpu_has_callbacks(int cpu) } /* + * Helper function for _rcu_barrier() tracing. If tracing is disabled, + * the compiler is expected to optimize this away. + */ +static void _rcu_barrier_trace(struct rcu_state *rsp, char *s, + int cpu, unsigned long done) +{ + trace_rcu_barrier(rsp->name, s, cpu, + atomic_read(&rsp->barrier_cpu_count), done); +} + +/* * RCU callback function for _rcu_barrier(). If we are last, wake * up the task executing _rcu_barrier(). */ @@ -2268,8 +2279,12 @@ static void rcu_barrier_callback(struct rcu_head *rhp) struct rcu_data *rdp = container_of(rhp, struct rcu_data, barrier_head); struct rcu_state *rsp = rdp->rsp; - if (atomic_dec_and_test(&rsp->barrier_cpu_count)) + if (atomic_dec_and_test(&rsp->barrier_cpu_count)) { + _rcu_barrier_trace(rsp, "LastCB", -1, rsp->n_barrier_done); complete(&rsp->barrier_completion); + } else { + _rcu_barrier_trace(rsp, "CB", -1, rsp->n_barrier_done); + } } /* @@ -2280,6 +2295,7 @@ static void rcu_barrier_func(void *type) struct rcu_state *rsp = type; struct rcu_data *rdp = __this_cpu_ptr(rsp->rda); + _rcu_barrier_trace(rsp, "IRQ", -1, rsp->n_barrier_done); atomic_inc(&rsp->barrier_cpu_count); rsp->call(&rdp->barrier_head, rcu_barrier_callback); } @@ -2298,6 +2314,7 @@ static void _rcu_barrier(struct rcu_state *rsp) unsigned long snap_done; init_rcu_head_on_stack(&rd.barrier_head); + _rcu_barrier_trace(rsp, "Begin", -1, snap); /* Take mutex to serialize concurrent rcu_barrier() requests. */ mutex_lock(&rsp->barrier_mutex); @@ -2315,7 +2332,9 @@ static void _rcu_barrier(struct rcu_state *rsp) * value up to the next even number and adds two before comparing. */ snap_done = ACCESS_ONCE(rsp->n_barrier_done); + _rcu_barrier_trace(rsp, "Check", -1, snap_done); if (ULONG_CMP_GE(snap_done, ((snap + 1) & ~0x1) + 2)) { + _rcu_barrier_trace(rsp, "EarlyExit", -1, snap_done); smp_mb(); /* caller's subsequent code after above check. */ mutex_unlock(&rsp->barrier_mutex); return; @@ -2328,6 +2347,7 @@ static void _rcu_barrier(struct rcu_state *rsp) */ ACCESS_ONCE(rsp->n_barrier_done)++; WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 1); + _rcu_barrier_trace(rsp, "Inc1", -1, rsp->n_barrier_done); smp_mb(); /* Order ->n_barrier_done increment with below mechanism. */ /* @@ -2364,13 +2384,19 @@ static void _rcu_barrier(struct rcu_state *rsp) preempt_disable(); rdp = per_cpu_ptr(rsp->rda, cpu); if (cpu_is_offline(cpu)) { + _rcu_barrier_trace(rsp, "Offline", cpu, + rsp->n_barrier_done); preempt_enable(); while (cpu_is_offline(cpu) && ACCESS_ONCE(rdp->qlen)) schedule_timeout_interruptible(1); } else if (ACCESS_ONCE(rdp->qlen)) { + _rcu_barrier_trace(rsp, "OnlineQ", cpu, + rsp->n_barrier_done); smp_call_function_single(cpu, rcu_barrier_func, rsp, 1); preempt_enable(); } else { + _rcu_barrier_trace(rsp, "OnlineNQ", cpu, + rsp->n_barrier_done); preempt_enable(); } } @@ -2403,6 +2429,7 @@ static void _rcu_barrier(struct rcu_state *rsp) smp_mb(); /* Keep increment after above mechanism. */ ACCESS_ONCE(rsp->n_barrier_done)++; WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 0); + _rcu_barrier_trace(rsp, "Inc2", -1, rsp->n_barrier_done); smp_mb(); /* Keep increment before caller's subsequent code. */ /* Wait for all rcu_barrier_callback() callbacks to be invoked. */ |