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| author | Paul E. McKenney <paulmck@kernel.org> | 2021-04-07 02:31:42 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-05-11 02:22:54 +0300 |
| commit | 396eba65f62414ee8850ed5f7b5ce844719ebebf (patch) | |
| tree | c199bb3e1f0ab831caa89a11cd45638331849ba7 /kernel/rcu | |
| parent | 3066820034b5dd4e89bd74a7739c51c2d6f5e554 (diff) | |
| download | linux-396eba65f62414ee8850ed5f7b5ce844719ebebf.tar.xz | |
rcu: Add quiescent states and boost states to show_rcu_gp_kthreads() output
This commit adds each rcu_node structure's ->qsmask and "bBEG" output
indicating whether: (1) There is a boost kthread, (2) A reader needs
to be (or is in the process of being) boosted, (3) A reader is blocking
an expedited grace period, and (4) A reader is blocking a normal grace
period. This helps diagnose RCU priority boosting failures.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.h | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree_stall.h | 12 |
3 files changed, 11 insertions, 3 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 71821d59d95c..5fd0c443517e 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -115,6 +115,7 @@ struct rcu_node { /* boosting for this rcu_node structure. */ unsigned int boost_kthread_status; /* State of boost_kthread_task for tracing. */ + unsigned long n_boosts; /* Number of boosts for this rcu_node structure. */ #ifdef CONFIG_RCU_NOCB_CPU struct swait_queue_head nocb_gp_wq[2]; /* Place for rcu_nocb_kthread() to wait GP. */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 2cbe8f8456e6..ef004cc7101d 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1098,6 +1098,7 @@ static int rcu_boost(struct rcu_node *rnp) /* Lock only for side effect: boosts task t's priority. */ rt_mutex_lock(&rnp->boost_mtx); rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */ + rnp->n_boosts++; return READ_ONCE(rnp->exp_tasks) != NULL || READ_ONCE(rnp->boost_tasks) != NULL; diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index a4e2bb3bdce7..c1f83864a18e 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -749,9 +749,15 @@ void show_rcu_gp_kthreads(void) if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), READ_ONCE(rnp->gp_seq_needed))) continue; - pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld\n", - rnp->grplo, rnp->grphi, (long)data_race(rnp->gp_seq), - (long)data_race(rnp->gp_seq_needed)); + pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld ->qsmask %#lx %c%c%c%c ->n_boosts %ld\n", + rnp->grplo, rnp->grphi, + (long)data_race(rnp->gp_seq), (long)data_race(rnp->gp_seq_needed), + data_race(rnp->qsmask), + ".b"[!!data_race(rnp->boost_kthread_task)], + ".B"[!!data_race(rnp->boost_tasks)], + ".E"[!!data_race(rnp->exp_tasks)], + ".G"[!!data_race(rnp->gp_tasks)], + data_race(rnp->n_boosts)); if (!rcu_is_leaf_node(rnp)) continue; for_each_leaf_node_possible_cpu(rnp, cpu) { |