diff options
Diffstat (limited to 'include/linux/rcu_segcblist.h')
| -rw-r--r-- | include/linux/rcu_segcblist.h | 144 |
1 files changed, 142 insertions, 2 deletions
diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h index b36afe7b22c9..659d13a7ddaa 100644 --- a/include/linux/rcu_segcblist.h +++ b/include/linux/rcu_segcblist.h @@ -63,6 +63,146 @@ struct rcu_cblist { #define RCU_NEXT_TAIL 3 #define RCU_CBLIST_NSEGS 4 + +/* + * ==NOCB Offloading state machine== + * + * + * ---------------------------------------------------------------------------- + * | SEGCBLIST_RCU_CORE | + * | | + * | Callbacks processed by rcu_core() from softirqs or local | + * | rcuc kthread, without holding nocb_lock. | + * ---------------------------------------------------------------------------- + * | + * v + * ---------------------------------------------------------------------------- + * | SEGCBLIST_RCU_CORE | SEGCBLIST_LOCKING | SEGCBLIST_OFFLOADED | + * | | + * | Callbacks processed by rcu_core() from softirqs or local | + * | rcuc kthread, while holding nocb_lock. Waking up CB and GP kthreads, | + * | allowing nocb_timer to be armed. | + * ---------------------------------------------------------------------------- + * | + * v + * ----------------------------------- + * | | + * v v + * --------------------------------------- ----------------------------------| + * | SEGCBLIST_RCU_CORE | | | SEGCBLIST_RCU_CORE | | + * | SEGCBLIST_LOCKING | | | SEGCBLIST_LOCKING | | + * | SEGCBLIST_OFFLOADED | | | SEGCBLIST_OFFLOADED | | + * | SEGCBLIST_KTHREAD_CB | | SEGCBLIST_KTHREAD_GP | + * | | | | + * | | | | + * | CB kthread woke up and | | GP kthread woke up and | + * | acknowledged SEGCBLIST_OFFLOADED. | | acknowledged SEGCBLIST_OFFLOADED| + * | Processes callbacks concurrently | | | + * | with rcu_core(), holding | | | + * | nocb_lock. | | | + * --------------------------------------- ----------------------------------- + * | | + * ----------------------------------- + * | + * v + * |--------------------------------------------------------------------------| + * | SEGCBLIST_LOCKING | | + * | SEGCBLIST_OFFLOADED | | + * | SEGCBLIST_KTHREAD_GP | | + * | SEGCBLIST_KTHREAD_CB | + * | | + * | Kthreads handle callbacks holding nocb_lock, local rcu_core() stops | + * | handling callbacks. Enable bypass queueing. | + * ---------------------------------------------------------------------------- + */ + + + +/* + * ==NOCB De-Offloading state machine== + * + * + * |--------------------------------------------------------------------------| + * | SEGCBLIST_LOCKING | | + * | SEGCBLIST_OFFLOADED | | + * | SEGCBLIST_KTHREAD_CB | | + * | SEGCBLIST_KTHREAD_GP | + * | | + * | CB/GP kthreads handle callbacks holding nocb_lock, local rcu_core() | + * | ignores callbacks. Bypass enqueue is enabled. | + * ---------------------------------------------------------------------------- + * | + * v + * |--------------------------------------------------------------------------| + * | SEGCBLIST_RCU_CORE | | + * | SEGCBLIST_LOCKING | | + * | SEGCBLIST_OFFLOADED | | + * | SEGCBLIST_KTHREAD_CB | | + * | SEGCBLIST_KTHREAD_GP | + * | | + * | CB/GP kthreads handle callbacks holding nocb_lock, local rcu_core() | + * | handles callbacks concurrently. Bypass enqueue is enabled. | + * | Invoke RCU core so we make sure not to preempt it in the middle with | + * | leaving some urgent work unattended within a jiffy. | + * ---------------------------------------------------------------------------- + * | + * v + * |--------------------------------------------------------------------------| + * | SEGCBLIST_RCU_CORE | | + * | SEGCBLIST_LOCKING | | + * | SEGCBLIST_KTHREAD_CB | | + * | SEGCBLIST_KTHREAD_GP | + * | | + * | CB/GP kthreads and local rcu_core() handle callbacks concurrently | + * | holding nocb_lock. Wake up CB and GP kthreads if necessary. Disable | + * | bypass enqueue. | + * ---------------------------------------------------------------------------- + * | + * v + * ----------------------------------- + * | | + * v v + * ---------------------------------------------------------------------------| + * | | | + * | SEGCBLIST_RCU_CORE | | SEGCBLIST_RCU_CORE | | + * | SEGCBLIST_LOCKING | | SEGCBLIST_LOCKING | | + * | SEGCBLIST_KTHREAD_CB | SEGCBLIST_KTHREAD_GP | + * | | | + * | GP kthread woke up and | CB kthread woke up and | + * | acknowledged the fact that | acknowledged the fact that | + * | SEGCBLIST_OFFLOADED got cleared. | SEGCBLIST_OFFLOADED got cleared. | + * | | The CB kthread goes to sleep | + * | The callbacks from the target CPU | until it ever gets re-offloaded. | + * | will be ignored from the GP kthread | | + * | loop. | | + * ---------------------------------------------------------------------------- + * | | + * ----------------------------------- + * | + * v + * ---------------------------------------------------------------------------- + * | SEGCBLIST_RCU_CORE | SEGCBLIST_LOCKING | + * | | + * | Callbacks processed by rcu_core() from softirqs or local | + * | rcuc kthread, while holding nocb_lock. Forbid nocb_timer to be armed. | + * | Flush pending nocb_timer. Flush nocb bypass callbacks. | + * ---------------------------------------------------------------------------- + * | + * v + * ---------------------------------------------------------------------------- + * | SEGCBLIST_RCU_CORE | + * | | + * | Callbacks processed by rcu_core() from softirqs or local | + * | rcuc kthread, without holding nocb_lock. | + * ---------------------------------------------------------------------------- + */ +#define SEGCBLIST_ENABLED BIT(0) +#define SEGCBLIST_RCU_CORE BIT(1) +#define SEGCBLIST_LOCKING BIT(2) +#define SEGCBLIST_KTHREAD_CB BIT(3) +#define SEGCBLIST_KTHREAD_GP BIT(4) +#define SEGCBLIST_OFFLOADED BIT(5) + struct rcu_segcblist { struct rcu_head *head; struct rcu_head **tails[RCU_CBLIST_NSEGS]; @@ -72,8 +212,8 @@ struct rcu_segcblist { #else long len; #endif - u8 enabled; - u8 offloaded; + long seglen[RCU_CBLIST_NSEGS]; + u8 flags; }; #define RCU_SEGCBLIST_INITIALIZER(n) \ |