This patch add the ability to dynamically configure processors for remote
rcu callback processing. It applies on top of PATCH 1/2.
Signed-off-by: Dimitri Sivanich <[email protected]>
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux/include/linux/rcupdate.h
===================================================================
--- linux.orig/include/linux/rcupdate.h 2006-04-03 15:26:38.743863052 -0500
+++ linux/include/linux/rcupdate.h 2006-04-03 15:26:43.863355795 -0500
@@ -109,6 +109,7 @@ struct rcu_data {
#ifdef CONFIG_SMP
long last_rs_qlen; /* qlen during the last resched */
spinlock_t rmlock; /* for use with remote callback */
+ short batch_stat; /* indicate processing being done */
#endif
};
Index: linux/kernel/rcupdate.c
===================================================================
--- linux.orig/kernel/rcupdate.c 2006-04-03 15:26:38.743863052 -0500
+++ linux/kernel/rcupdate.c 2006-04-03 15:26:43.867355399 -0500
@@ -195,7 +195,7 @@ static int rcu_next_remotercu(void)
/*
* Configure a cpu for remote rcu callback processing.
*/
-static int rcu_set_remote_rcu(int cpu) {
+int rcu_set_remote_rcu(int cpu) {
unsigned long flags;
if (cpu < NR_CPUS) {
@@ -206,11 +206,12 @@ static int rcu_set_remote_rcu(int cpu) {
} else
return 1;
}
+EXPORT_SYMBOL_GPL(rcu_set_remote_rcu);
/*
* Configure a cpu for standard rcu callback processing.
*/
-static void rcu_clear_remote_rcu(int cpu) {
+void rcu_clear_remote_rcu(int cpu) {
unsigned long flags;
if (cpu < NR_CPUS) {
@@ -219,6 +220,7 @@ static void rcu_clear_remote_rcu(int cpu
spin_unlock_irqrestore(&cpu_remotercu_lock, flags);
}
}
+EXPORT_SYMBOL_GPL(rcu_clear_remote_rcu);
/*
* Configure a set of cpus at boot time for remote rcu callback
@@ -238,7 +240,6 @@ static int __init rcu_remotercu_cpu_setu
__setup ("remotercu=", rcu_remotercu_cpu_setup);
#else
-static int rcu_callbacks_processed_remotely(int cpu) { return 0; }
static int rcu_process_remote(int cpu) { return 0; }
static void rcu_clear_remote_rcu(int cpu) {}
#endif
@@ -650,8 +651,16 @@ static void __rcu_process_callbacks(stru
}
rcu_check_quiescent_state(rcp, rdp);
- if (!rcu_callbacks_processed_remotely(cpu) && rdp->donelist)
+#ifdef CONFIG_NUMA
+ if (rdp->donelist && !rcu_callbacks_processed_remotely(cpu) &&
+ (cmpxchg(&rdp->batch_stat, 0, 1)) == 0) {
rcu_do_batch(rdp);
+ rdp->batch_stat = 0;
+ }
+#else
+ if (rdp->donelist)
+ rcu_do_batch(rdp);
+#endif
}
static void rcu_process_callbacks(unsigned long unused)
@@ -692,15 +701,25 @@ static void rcu_process_remote_callbacks
*/
rdp = &per_cpu(rcu_data, cpu);
if (spin_trylock_irq(&rdp->rmlock)) {
- if ((list=xchg(&rdp->donelist, NULL))!=NULL)
- rdp->donetail = &rdp->donelist;
+ /*
+ * batch_stat ensures cpu isn't still running rcu_do_batch.
+ * This can happen if we've just configured on the fly.
+ */
+ if (cmpxchg(&rdp->batch_stat, 0, 2) == 0) {
+ list=xchg(&rdp->donelist, NULL);
+ if (list != NULL)
+ rdp->donetail = &rdp->donelist;
+ }
spin_unlock_irq(&rdp->rmlock);
}
rdp_bh = &per_cpu(rcu_bh_data, cpu);
if (spin_trylock_irq(&rdp_bh->rmlock)) {
- if ((list_bh=xchg(&rdp_bh->donelist, NULL))!=NULL)
- rdp_bh->donetail = &rdp_bh->donelist;
+ if (cmpxchg(&rdp_bh->batch_stat, 0, 2) == 0) {
+ list_bh=xchg(&rdp_bh->donelist, NULL);
+ if (list_bh != NULL)
+ rdp_bh->donetail = &rdp_bh->donelist;
+ }
spin_unlock_irq(&rdp_bh->rmlock);
}
@@ -717,6 +736,8 @@ static void rcu_process_remote_callbacks
old = rdp->qlen;
new = old - cnt;
} while (cmpxchg(&rdp->qlen, old, new)!=old);
+ if (rdp->batch_stat == 2)
+ rdp->batch_stat = 0;
cnt=0;
while (list_bh) {
@@ -729,6 +750,8 @@ static void rcu_process_remote_callbacks
old = rdp_bh->qlen;
new = old - cnt;
} while (cmpxchg(&rdp_bh->qlen, old, new)!=old);
+ if (rdp_bh->batch_stat == 2)
+ rdp_bh->batch_stat = 0;
}
#else
static void rcu_process_remote_callbacks(unsigned long unused) {}
-
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