From 2cc78eb52bc1ae89f0a4fa5a00eb998dffde4a9f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 17 Oct 2005 09:10:15 -0700 Subject: Increase default RCU batching sharply Dipankar made RCU limit the batch size to improve latency, but that approach is unworkable: it can cause the RCU queues to grow without bounds, since the batch limiter ended up limiting the callbacks. So make the limit much higher, and start planning on instead limiting the batch size by doing RCU callbacks more often if the queue looks like it might be growing too long. Signed-off-by: Linus Torvalds --- kernel/rcupdate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/rcupdate.c') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index bef3b69..dd99415 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -71,7 +71,7 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; /* Fake initialization required by compiler */ static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL}; -static int maxbatch = 10; +static int maxbatch = 10000; #ifndef __HAVE_ARCH_CMPXCHG /* -- cgit v1.1 From 5ee832dbc6770135ec8d63296af0a4374557bb79 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 17 Oct 2005 20:01:21 +0200 Subject: [PATCH] rcu: keep rcu callback event counter This makes call_rcu() keep track of how many events there are on the RCU list, and cause a reschedule event when the list gets too long. This helps keep RCU event lists down. Signed-off-by: Linus Torvalds --- kernel/rcupdate.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'kernel/rcupdate.c') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index dd99415..2559d4b 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -109,6 +109,10 @@ void fastcall call_rcu(struct rcu_head *head, rdp = &__get_cpu_var(rcu_data); *rdp->nxttail = head; rdp->nxttail = &head->next; + + if (unlikely(++rdp->count > 10000)) + set_need_resched(); + local_irq_restore(flags); } @@ -140,6 +144,12 @@ void fastcall call_rcu_bh(struct rcu_head *head, rdp = &__get_cpu_var(rcu_bh_data); *rdp->nxttail = head; rdp->nxttail = &head->next; + rdp->count++; +/* + * Should we directly call rcu_do_batch() here ? + * if (unlikely(rdp->count > 10000)) + * rcu_do_batch(rdp); + */ local_irq_restore(flags); } @@ -157,6 +167,7 @@ static void rcu_do_batch(struct rcu_data *rdp) next = rdp->donelist = list->next; list->func(list); list = next; + rdp->count--; if (++count >= maxbatch) break; } -- cgit v1.1