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| author | Frederic Weisbecker <frederic@kernel.org> | 2021-10-19 02:08:14 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-12-08 01:24:44 +0100 |
| commit | 3e61e95e2d095e308616cba4ffb640f95a480e01 (patch) | |
| tree | 1162e479249a36a79f6529a1b3cb68b36d35c793 /kernel/rcu/tree.c | |
| parent | rcu/nocb: Limit number of softirq callbacks only on softirq (diff) | |
| download | linux-3e61e95e2d095e308616cba4ffb640f95a480e01.tar.xz linux-3e61e95e2d095e308616cba4ffb640f95a480e01.zip | |
rcu: Fix callbacks processing time limit retaining cond_resched()
The callbacks processing time limit makes sure we are not exceeding a
given amount of time executing the queue.
However its "continue" clause bypasses the cond_resched() call on
rcuc and NOCB kthreads, delaying it until we reach the limit, which can
be very long...
Make sure the scheduler has a higher priority than the time limit.
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 4f4d9ea6a9cb..74e210ccfd38 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2525,9 +2525,21 @@ static void rcu_do_batch(struct rcu_data *rdp) /* * Stop only if limit reached and CPU has something to do. */ - if (count >= bl && in_serving_softirq() && - (need_resched() || !is_idle_task(current))) - break; + if (in_serving_softirq()) { + if (count >= bl && (need_resched() || !is_idle_task(current))) + break; + } else { + local_bh_enable(); + lockdep_assert_irqs_enabled(); + cond_resched_tasks_rcu_qs(); + lockdep_assert_irqs_enabled(); + local_bh_disable(); + } + + /* + * Make sure we don't spend too much time here and deprive other + * softirq vectors of CPU cycles. + */ if (unlikely(tlimit)) { /* only call local_clock() every 32 callbacks */ if (likely((count & 31) || local_clock() < tlimit)) @@ -2535,13 +2547,6 @@ static void rcu_do_batch(struct rcu_data *rdp) /* Exceeded the time limit, so leave. */ break; } - if (!in_serving_softirq()) { - local_bh_enable(); - lockdep_assert_irqs_enabled(); - cond_resched_tasks_rcu_qs(); - lockdep_assert_irqs_enabled(); - local_bh_disable(); - } } rcu_nocb_lock_irqsave(rdp, flags); |