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-rw-r--r--Documentation/kernel-parameters.txt13
-rw-r--r--include/linux/rcupdate.h6
-rw-r--r--kernel/rcupdate.c76
3 files changed, 76 insertions, 19 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 75205391b33..bad5987c472 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1284,6 +1284,19 @@ running once the system is up.
New name for the ramdisk parameter.
See Documentation/ramdisk.txt.
+ rcu.blimit= [KNL,BOOT] Set maximum number of finished
+ RCU callbacks to process in one batch.
+
+ rcu.qhimark= [KNL,BOOT] Set threshold of queued
+ RCU callbacks over which batch limiting is disabled.
+
+ rcu.qlowmark= [KNL,BOOT] Set threshold of queued
+ RCU callbacks below which batch limiting is re-enabled.
+
+ rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
+ RCU callbacks to queued before forcing reschedule
+ on all cpus.
+
rdinit= [KNL]
Format: <full_path>
Run specified binary instead of /init from the ramdisk,
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index b87aefa082e..c2ec6c77874 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -98,13 +98,17 @@ struct rcu_data {
long batch; /* Batch # for current RCU batch */
struct rcu_head *nxtlist;
struct rcu_head **nxttail;
- long count; /* # of queued items */
+ long qlen; /* # of queued callbacks */
struct rcu_head *curlist;
struct rcu_head **curtail;
struct rcu_head *donelist;
struct rcu_head **donetail;
+ long blimit; /* Upper limit on a processed batch */
int cpu;
struct rcu_head barrier;
+#ifdef CONFIG_SMP
+ long last_rs_qlen; /* qlen during the last resched */
+#endif
};
DECLARE_PER_CPU(struct rcu_data, rcu_data);
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 0cf8146bd58..8cf15a569fc 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -67,7 +67,43 @@ 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 = 10000;
+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 struct semaphore rcu_barrier_sema;
+static struct completion rcu_barrier_completion;
+
+#ifdef CONFIG_SMP
+static void force_quiescent_state(struct rcu_data *rdp,
+ struct rcu_ctrlblk *rcp)
+{
+ int cpu;
+ cpumask_t cpumask;
+ set_need_resched();
+ if (unlikely(rdp->qlen - rdp->last_rs_qlen > rsinterval)) {
+ rdp->last_rs_qlen = rdp->qlen;
+ /*
+ * Don't send IPI to itself. With irqs disabled,
+ * rdp->cpu is the current cpu.
+ */
+ cpumask = rcp->cpumask;
+ cpu_clear(rdp->cpu, cpumask);
+ for_each_cpu_mask(cpu, cpumask)
+ smp_send_reschedule(cpu);
+ }
+}
+#else
+static inline void force_quiescent_state(struct rcu_data *rdp,
+ struct rcu_ctrlblk *rcp)
+{
+ set_need_resched();
+}
+#endif
/**
* call_rcu - Queue an RCU callback for invocation after a grace period.
@@ -92,17 +128,13 @@ 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();
-
+ if (unlikely(++rdp->qlen > qhimark)) {
+ rdp->blimit = INT_MAX;
+ force_quiescent_state(rdp, &rcu_ctrlblk);
+ }
local_irq_restore(flags);
}
-static atomic_t rcu_barrier_cpu_count;
-static struct semaphore rcu_barrier_sema;
-static struct completion rcu_barrier_completion;
-
/**
* call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
* @head: structure to be used for queueing the RCU updates.
@@ -131,12 +163,12 @@ 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);
- */
+
+ if (unlikely(++rdp->qlen > qhimark)) {
+ rdp->blimit = INT_MAX;
+ force_quiescent_state(rdp, &rcu_bh_ctrlblk);
+ }
+
local_irq_restore(flags);
}
@@ -199,10 +231,12 @@ static void rcu_do_batch(struct rcu_data *rdp)
next = rdp->donelist = list->next;
list->func(list);
list = next;
- rdp->count--;
- if (++count >= maxbatch)
+ rdp->qlen--;
+ if (++count >= rdp->blimit)
break;
}
+ if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark)
+ rdp->blimit = blimit;
if (!rdp->donelist)
rdp->donetail = &rdp->donelist;
else
@@ -473,6 +507,7 @@ static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp,
rdp->quiescbatch = rcp->completed;
rdp->qs_pending = 0;
rdp->cpu = cpu;
+ rdp->blimit = blimit;
}
static void __devinit rcu_online_cpu(int cpu)
@@ -567,7 +602,12 @@ void synchronize_kernel(void)
synchronize_rcu();
}
-module_param(maxbatch, int, 0);
+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(call_rcu); /* WARNING: GPL-only in April 2006. */
EXPORT_SYMBOL(call_rcu_bh); /* WARNING: GPL-only in April 2006. */