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| author | Frederic Weisbecker <frederic@kernel.org> | 2021-02-23 03:10:11 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-05-12 22:10:23 +0300 |
| commit | e75bcd48e2c4026b1f3feda916a2327b1744d664 (patch) | |
| tree | 1891eba686d079afc2ed4370282e2d58cb624b97 /kernel/rcu/tree.h | |
| parent | 870905169da8bfae0570df013efe860d33251b0f (diff) | |
| download | linux-e75bcd48e2c4026b1f3feda916a2327b1744d664.tar.xz | |
rcu/nocb: Unify timers
Now that ->nocb_timer and ->nocb_bypass_timer have become quite similar,
this commit merges them together. A new RCU_NOCB_WAKE_BYPASS wake level
is introduced. As a result, timers perform all kinds of deferred wake
ups but other deferred wakeup callsites only handle non-bypass wakeups
in order not to wake up rcuo too early.
The timer also unconditionally executes a full barrier so as to order
timer_pending() and callback enqueue although the path performing
RCU_NOCB_WAKE_FORCE that makes use of it is debatable. It should also
test against the rdp leader instead of the current rdp.
This unconditional full barrier shouldn't bring visible overhead since
these timers almost never fire.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree.h')
| -rw-r--r-- | kernel/rcu/tree.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 2510e86265c1..9a16487edfca 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -218,7 +218,6 @@ struct rcu_data { /* The following fields are used by GP kthread, hence own cacheline. */ raw_spinlock_t nocb_gp_lock ____cacheline_internodealigned_in_smp; - struct timer_list nocb_bypass_timer; /* Force nocb_bypass flush. */ u8 nocb_gp_sleep; /* Is the nocb GP thread asleep? */ u8 nocb_gp_bypass; /* Found a bypass on last scan? */ u8 nocb_gp_gp; /* GP to wait for on last scan? */ @@ -258,8 +257,9 @@ struct rcu_data { /* Values for nocb_defer_wakeup field in struct rcu_data. */ #define RCU_NOCB_WAKE_NOT 0 -#define RCU_NOCB_WAKE 1 -#define RCU_NOCB_WAKE_FORCE 2 +#define RCU_NOCB_WAKE_BYPASS 1 +#define RCU_NOCB_WAKE 2 +#define RCU_NOCB_WAKE_FORCE 3 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) /* For jiffies_till_first_fqs and */ |