diff options
| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2013-01-07 13:37:42 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-03-12 11:17:51 -0700 |
| commit | 34ed62461ae4970695974afb9a60ac3df0086830 (patch) | |
| tree | d65a582953a66ee089074fd5a57e39460d4ce2c6 /kernel/rcutree.h | |
| parent | f6161aa153581da4a3867a2d1a7caf4be19b6ec9 (diff) | |
rcu: Remove restrictions on no-CBs CPUs
Currently, CPU 0 is constrained to not be a no-CBs CPU, and furthermore
at least one no-CBs CPU must remain online at any given time. These
restrictions are problematic in some situations, such as cases where
all CPUs must run a real-time workload that needs to be insulated from
OS jitter and latencies due to RCU callback invocation. This commit
therefore provides no-CBs CPUs a (very crude and energy-inefficient)
way to start and to wait for grace periods independently of the normal
RCU callback mechanisms. This approach allows any or all of the CPUs to
be designated as no-CBs CPUs, and allows any proper subset of the CPUs
(whether no-CBs CPUs or not) to be offlined.
This commit also provides a fix for a locking bug spotted by Xie
ChanglongX <changlongx.xie@intel.com>.
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.h')
| -rw-r--r-- | kernel/rcutree.h | 12 |
1 files changed, 3 insertions, 9 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h index c896b5045d9d..7af39f4aaac4 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -326,6 +326,7 @@ struct rcu_data { int nocb_p_count_lazy; /* (approximate). */ wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */ struct task_struct *nocb_kthread; + bool nocb_needs_gp; #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ int cpu; @@ -375,12 +376,6 @@ struct rcu_state { struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ void (*call)(struct rcu_head *head, /* call_rcu() flavor. */ void (*func)(struct rcu_head *head)); -#ifdef CONFIG_RCU_NOCB_CPU - void (*call_remote)(struct rcu_head *head, - void (*func)(struct rcu_head *head)); - /* call_rcu() flavor, but for */ - /* placing on remote CPU. */ -#endif /* #ifdef CONFIG_RCU_NOCB_CPU */ /* The following fields are guarded by the root rcu_node's lock. */ @@ -529,16 +524,15 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); static void print_cpu_stall_info_end(void); static void zero_cpu_stall_ticks(struct rcu_data *rdp); static void increment_cpu_stall_ticks(void); +static int rcu_nocb_needs_gp(struct rcu_data *rdp); static bool is_nocb_cpu(int cpu); static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, bool lazy); static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, struct rcu_data *rdp); -static bool nocb_cpu_expendable(int cpu); static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp); -static void init_nocb_callback_list(struct rcu_data *rdp); -static void __init rcu_init_nocb(void); +static bool init_nocb_callback_list(struct rcu_data *rdp); #endif /* #ifndef RCU_TREE_NONCORE */ |