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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2011-11-22 14:58:03 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-12-11 10:32:00 -0800 |
| commit | 433cdddcd9ac5558068edd7f8d4707a70f7710f5 (patch) | |
| tree | 7f3686eb64c9ee3a239e5920df588c70837c5637 /kernel/rcutree_plugin.h | |
| parent | 045fb9315a2129023d70a0eecf0942e18fca4fcd (diff) | |
| download | lwn-433cdddcd9ac5558068edd7f8d4707a70f7710f5.tar.gz lwn-433cdddcd9ac5558068edd7f8d4707a70f7710f5.zip | |
rcu: Add tracing for RCU_FAST_NO_HZ
This commit adds trace_rcu_prep_idle(), which is invoked from
rcu_prepare_for_idle() and rcu_wake_cpu() to trace attempts on
the part of RCU to force CPUs into dyntick-idle mode.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree_plugin.h')
| -rw-r--r-- | kernel/rcutree_plugin.h | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index b70ca8cc52e1..6467f5669ab7 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -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(); } |