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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-10-04 02:17:17 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-04 07:55:31 -0700 |
| commit | 20e9751bd9dd6b832fd84ada27840360f7e877f1 (patch) | |
| tree | c598ff9cb9e540da7f8595f2c130f3674065e018 /kernel | |
| parent | 4b6c2cca6eef9cc4a15350bf1c61839e12e08b84 (diff) | |
| download | linux-20e9751bd9dd6b832fd84ada27840360f7e877f1.tar.gz linux-20e9751bd9dd6b832fd84ada27840360f7e877f1.tar.bz2 linux-20e9751bd9dd6b832fd84ada27840360f7e877f1.zip | |
[PATCH] rcu: simplify/improve batch tuning
Kill a hard-to-calculate 'rsinterval' boot parameter and per-cpu
rcu_data.last_rs_qlen. Instead, it adds adds a flag rcu_ctrlblk.signaled,
which records the fact that one of CPUs has sent a resched IPI since the
last rcu_start_batch().
Roughly speaking, we need two rcu_start_batch()s in order to move callbacks
from ->nxtlist to ->donelist. This means that when ->qlen exceeds qhimark
and continues to grow, we should send a resched IPI, and then do it again
after we gone through a quiescent state.
On the other hand, if it was already sent, we don't need to do it again
when another CPU detects overflow of the queue.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcupdate.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 523e46483b99..26bb5ffe1ef1 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -71,9 +71,6 @@ static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL}; static int blimit = 10; static int qhimark = 10000; static int qlowmark = 100; -#ifdef CONFIG_SMP -static int rsinterval = 1000; -#endif static atomic_t rcu_barrier_cpu_count; static DEFINE_MUTEX(rcu_barrier_mutex); @@ -86,8 +83,8 @@ static void force_quiescent_state(struct rcu_data *rdp, int cpu; cpumask_t cpumask; set_need_resched(); - if (unlikely(rdp->qlen - rdp->last_rs_qlen > rsinterval)) { - rdp->last_rs_qlen = rdp->qlen; + if (unlikely(!rcp->signaled)) { + rcp->signaled = 1; /* * Don't send IPI to itself. With irqs disabled, * rdp->cpu is the current cpu. @@ -301,6 +298,7 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp) smp_mb(); cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask); + rcp->signaled = 0; } } @@ -628,9 +626,6 @@ void synchronize_rcu(void) module_param(blimit, int, 0); module_param(qhimark, int, 0); module_param(qlowmark, int, 0); -#ifdef CONFIG_SMP -module_param(rsinterval, int, 0); -#endif EXPORT_SYMBOL_GPL(rcu_batches_completed); EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); EXPORT_SYMBOL_GPL(call_rcu); |