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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-04-26 11:52:09 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-07-12 14:27:46 -0700 |
| commit | de30ad512a668b56e7ad7a5a7c379d7c5d138a94 (patch) | |
| tree | b738dc4cef2074311f09b55da11f1a74a72acf72 /kernel/rcu/tree.h | |
| parent | 609af1cdf040f8d3f3986755586f7833eaa96d2c (diff) | |
| download | linux-de30ad512a668b56e7ad7a5a7c379d7c5d138a94.tar.bz2 | |
rcu: Introduce grace-period sequence numbers
This commit adds grace-period sequence numbers (->gp_seq) to the
rcu_state, rcu_node, and rcu_data structures, and updates them.
It also checks for consistency between rsp->gpnum and rsp->gp_seq.
These ->gp_seq counters will eventually replace the existing ->gpnum
and ->completed counters, allowing a single memory access to determine
whether or not a grace period is in progress and if so, which one.
This in turn will enable changes that will reduce ->lock contention on
the leaf rcu_node structures.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.h')
| -rw-r--r-- | kernel/rcu/tree.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 3c1942174c56..50a28d1cf5a1 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -87,6 +87,7 @@ struct rcu_node { unsigned long completed; /* Last GP completed for this node. */ /* This will either be equal to or one */ /* behind the root rcu_node's gpnum. */ + unsigned long gp_seq; /* Track rsp->rcu_gp_seq. */ unsigned long completedqs; /* All QSes done for this node. */ unsigned long qsmask; /* CPUs or groups that need to switch in */ /* order for current grace period to proceed.*/ @@ -211,6 +212,7 @@ struct rcu_data { /* in order to detect GP end. */ unsigned long gpnum; /* Highest gp number that this CPU */ /* is aware of having started. */ + unsigned long gp_seq; /* Track rsp->rcu_gp_seq counter. */ unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ /* for rcu_all_qs() invocations. */ union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */ @@ -343,6 +345,7 @@ struct rcu_state { /* Subject to priority boost. */ unsigned long gpnum; /* Current gp number. */ unsigned long completed; /* # of last completed gp. */ + unsigned long gp_seq; /* Grace-period sequence #. */ struct task_struct *gp_kthread; /* Task for grace periods. */ struct swait_queue_head gp_wq; /* Where GP task waits. */ short gp_flags; /* Commands for GP task. */ |