Avoid calling smp_processor_id in spl_magazine_age

The spl_magazine_age function had the implied assumption that it will
remain on its current cpu through its execution. In order to support
preempt enabled kernels, this assumption had to be removed.

The spl_kmem_magazine structure now holds the cpu id of the cpu it is
local to. This allows spl_magazine_age to use this field when scheduling
work to be done by the magazine's local cpu.

Signed-off-by: Brian Behlendorf <[email protected]>
Issue #98

2 files changed, 7 insertions, 6 deletions

diff --git a/include/sys/kmem.h b/include/sys/kmem.h
index 4383efb7c..344e2716b 100644
--- a/include/sys/kmem.h
+++ b/include/sys/kmem.h
@@ -353,6 +353,7 @@ typedef struct spl_kmem_magazine {
 	struct spl_kmem_cache	*skm_cache;	/* Owned by cache */
 	struct delayed_work	skm_work;	/* Magazine reclaim work */
 	unsigned long		skm_age;	/* Last cache access */
+	unsigned int		skm_cpu;	/* Owned by cpu */
 	void			*skm_objs[0];	/* Object pointers */
 } spl_kmem_magazine_t;
 
diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index 28afc6024..258d61478 100644
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -1156,18 +1156,17 @@ spl_magazine_age(void *data)
 	spl_kmem_magazine_t *skm =
 		spl_get_work_data(data, spl_kmem_magazine_t, skm_work.work);
 	spl_kmem_cache_t *skc = skm->skm_cache;
-	int i = smp_processor_id();
 
 	ASSERT(skm->skm_magic == SKM_MAGIC);
 	ASSERT(skc->skc_magic == SKC_MAGIC);
-	ASSERT(skc->skc_mag[i] == skm);
+	ASSERT(skc->skc_mag[skm->skm_cpu] == skm);
 
 	if (skm->skm_avail > 0 &&
 	    time_after(jiffies, skm->skm_age + skc->skc_delay * HZ))
 		(void)spl_cache_flush(skc, skm, skm->skm_refill);
 
 	if (!test_bit(KMC_BIT_DESTROY, &skc->skc_flags))
-		schedule_delayed_work_on(i, &skm->skm_work,
+		schedule_delayed_work_on(skm->skm_cpu, &skm->skm_work,
 					 skc->skc_delay / 3 * HZ);
 }
 
@@ -1267,14 +1266,14 @@ spl_magazine_size(spl_kmem_cache_t *skc)
  * Allocate a per-cpu magazine to associate with a specific core.
  */
 static spl_kmem_magazine_t *
-spl_magazine_alloc(spl_kmem_cache_t *skc, int node)
+spl_magazine_alloc(spl_kmem_cache_t *skc, int cpu)
 {
 	spl_kmem_magazine_t *skm;
 	int size = sizeof(spl_kmem_magazine_t) +
 	           sizeof(void *) * skc->skc_mag_size;
 	SENTRY;
 
-	skm = kmem_alloc_node(size, KM_SLEEP, node);
+	skm = kmem_alloc_node(size, KM_SLEEP, cpu_to_node(cpu));
 	if (skm) {
 		skm->skm_magic = SKM_MAGIC;
 		skm->skm_avail = 0;
@@ -1283,6 +1282,7 @@ spl_magazine_alloc(spl_kmem_cache_t *skc, int node)
 		skm->skm_cache = skc;
 		spl_init_delayed_work(&skm->skm_work, spl_magazine_age, skm);
 		skm->skm_age = jiffies;
+		skm->skm_cpu = cpu;
 	}
 
 	SRETURN(skm);
@@ -1318,7 +1318,7 @@ spl_magazine_create(spl_kmem_cache_t *skc)
 	skc->skc_mag_refill = (skc->skc_mag_size + 1) / 2;
 
 	for_each_online_cpu(i) {
-		skc->skc_mag[i] = spl_magazine_alloc(skc, cpu_to_node(i));
+		skc->skc_mag[i] = spl_magazine_alloc(skc, i);
 		if (!skc->skc_mag[i]) {
 			for (i--; i >= 0; i--)
 				spl_magazine_free(skc->skc_mag[i]);