Date:	Mon, 29 Mar 2010 17:12:39 +0300
From:	Timo Teras <timo.teras@....fi>
To:	netdev@...r.kernel.org
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	Timo Teras <timo.teras@....fi>
Subject: [PATCH 2/7] flow: structurize flow cache

Group all per-cpu data to one structure instead of having many
globals. Also prepare the internals so that we can have multiple
instances of the flow cache if needed.

Only the kmem_cache is left as a global as all flow caches share
the same element size, and benefit from using a common cache.

Signed-off-by: Timo Teras <timo.teras@....fi>
---
 net/core/flow.c |  223 +++++++++++++++++++++++++++++--------------------------
 1 files changed, 119 insertions(+), 104 deletions(-)

diff --git a/net/core/flow.c b/net/core/flow.c
index 9601587..1d27ca6 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -35,104 +35,105 @@ struct flow_cache_entry {
 	atomic_t		*object_ref;
 };
 
-atomic_t flow_cache_genid = ATOMIC_INIT(0);
-
-static u32 flow_hash_shift;
-#define flow_hash_size	(1 << flow_hash_shift)
-static DEFINE_PER_CPU(struct flow_cache_entry **, flow_tables) = { NULL };
-
-#define flow_table(cpu) (per_cpu(flow_tables, cpu))
-
-static struct kmem_cache *flow_cachep __read_mostly;
-
-static int flow_lwm, flow_hwm;
-
-struct flow_percpu_info {
-	int hash_rnd_recalc;
-	u32 hash_rnd;
-	int count;
+struct flow_cache_percpu {
+	struct flow_cache_entry **	hash_table;
+	int				hash_count;
+	u32				hash_rnd;
+	int				hash_rnd_recalc;
+	struct tasklet_struct		flush_tasklet;
 };
-static DEFINE_PER_CPU(struct flow_percpu_info, flow_hash_info) = { 0 };
-
-#define flow_hash_rnd_recalc(cpu) \
-	(per_cpu(flow_hash_info, cpu).hash_rnd_recalc)
-#define flow_hash_rnd(cpu) \
-	(per_cpu(flow_hash_info, cpu).hash_rnd)
-#define flow_count(cpu) \
-	(per_cpu(flow_hash_info, cpu).count)
-
-static struct timer_list flow_hash_rnd_timer;
-
-#define FLOW_HASH_RND_PERIOD	(10 * 60 * HZ)
 
 struct flow_flush_info {
-	atomic_t cpuleft;
-	struct completion completion;
+	struct flow_cache *		cache;
+	atomic_t			cpuleft;
+	struct completion		completion;
 };
-static DEFINE_PER_CPU(struct tasklet_struct, flow_flush_tasklets) = { NULL };
 
-#define flow_flush_tasklet(cpu) (&per_cpu(flow_flush_tasklets, cpu))
+struct flow_cache {
+	u32				hash_shift;
+	unsigned long			order;
+	struct flow_cache_percpu *	percpu;
+	struct notifier_block		hotcpu_notifier;
+	int				low_watermark;
+	int				high_watermark;
+	struct timer_list		rnd_timer;
+};
+
+atomic_t flow_cache_genid = ATOMIC_INIT(0);
+static struct flow_cache flow_cache_global;
+static struct kmem_cache *flow_cachep;
+
+#define flow_cache_hash_size(cache)	(1 << (cache)->hash_shift)
+#define FLOW_HASH_RND_PERIOD		(10 * 60 * HZ)
 
 static void flow_cache_new_hashrnd(unsigned long arg)
 {
+	struct flow_cache *fc = (void *) arg;
 	int i;
 
 	for_each_possible_cpu(i)
-		flow_hash_rnd_recalc(i) = 1;
+		per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
 
-	flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
-	add_timer(&flow_hash_rnd_timer);
+	fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+	add_timer(&fc->rnd_timer);
 }
 
-static void flow_entry_kill(int cpu, struct flow_cache_entry *fle)
+static void flow_entry_kill(struct flow_cache *fc,
+			    struct flow_cache_percpu *fcp,
+			    struct flow_cache_entry *fle)
 {
 	if (fle->object)
 		atomic_dec(fle->object_ref);
 	kmem_cache_free(flow_cachep, fle);
-	flow_count(cpu)--;
+	fcp->hash_count--;
 }
 
-static void __flow_cache_shrink(int cpu, int shrink_to)
+static void __flow_cache_shrink(struct flow_cache *fc,
+				struct flow_cache_percpu *fcp,
+				int shrink_to)
 {
 	struct flow_cache_entry *fle, **flp;
 	int i;
 
-	for (i = 0; i < flow_hash_size; i++) {
+	for (i = 0; i < flow_cache_hash_size(fc); i++) {
 		int k = 0;
 
-		flp = &flow_table(cpu)[i];
+		flp = &fcp->hash_table[i];
 		while ((fle = *flp) != NULL && k < shrink_to) {
 			k++;
 			flp = &fle->next;
 		}
 		while ((fle = *flp) != NULL) {
 			*flp = fle->next;
-			flow_entry_kill(cpu, fle);
+			flow_entry_kill(fc, fcp, fle);
 		}
 	}
 }
 
-static void flow_cache_shrink(int cpu)
+static void flow_cache_shrink(struct flow_cache *fc,
+			      struct flow_cache_percpu *fcp)
 {
-	int shrink_to = flow_lwm / flow_hash_size;
+	int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
 
-	__flow_cache_shrink(cpu, shrink_to);
+	__flow_cache_shrink(fc, fcp, shrink_to);
 }
 
-static void flow_new_hash_rnd(int cpu)
+static void flow_new_hash_rnd(struct flow_cache *fc,
+			      struct flow_cache_percpu *fcp)
 {
-	get_random_bytes(&flow_hash_rnd(cpu), sizeof(u32));
-	flow_hash_rnd_recalc(cpu) = 0;
-
-	__flow_cache_shrink(cpu, 0);
+	get_random_bytes(&fcp->hash_rnd, sizeof(u32));
+	fcp->hash_rnd_recalc = 0;
+	__flow_cache_shrink(fc, fcp, 0);
 }
 
-static u32 flow_hash_code(struct flowi *key, int cpu)
+static u32 flow_hash_code(struct flow_cache *fc,
+			  struct flow_cache_percpu *fcp,
+			  struct flowi *key)
 {
 	u32 *k = (u32 *) key;
 
-	return (jhash2(k, (sizeof(*key) / sizeof(u32)), flow_hash_rnd(cpu)) &
-		(flow_hash_size - 1));
+	return (jhash2(k, (sizeof(*key) / sizeof(u32)), fcp->hash_rnd)
+		& (flow_cache_hash_size(fc) - 1));
 }
 
 #if (BITS_PER_LONG == 64)
@@ -168,24 +169,25 @@ static int flow_key_compare(struct flowi *key1, struct flowi *key2)
 void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
 			flow_resolve_t resolver)
 {
+	struct flow_cache *fc = &flow_cache_global;
+	struct flow_cache_percpu *fcp;
 	struct flow_cache_entry *fle, **head;
 	unsigned int hash;
-	int cpu;
 
 	local_bh_disable();
-	cpu = smp_processor_id();
+	fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
 
 	fle = NULL;
 	/* Packet really early in init?  Making flow_cache_init a
 	 * pre-smp initcall would solve this.  --RR */
-	if (!flow_table(cpu))
+	if (!fcp->hash_table)
 		goto nocache;
 
-	if (flow_hash_rnd_recalc(cpu))
-		flow_new_hash_rnd(cpu);
-	hash = flow_hash_code(key, cpu);
+	if (fcp->hash_rnd_recalc)
+		flow_new_hash_rnd(fc, fcp);
+	hash = flow_hash_code(fc, fcp, key);
 
-	head = &flow_table(cpu)[hash];
+	head = &fcp->hash_table[hash];
 	for (fle = *head; fle; fle = fle->next) {
 		if (fle->family == family &&
 		    fle->dir == dir &&
@@ -204,8 +206,8 @@ void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
 	}
 
 	if (!fle) {
-		if (flow_count(cpu) > flow_hwm)
-			flow_cache_shrink(cpu);
+		if (fcp->hash_count > fc->high_watermark)
+			flow_cache_shrink(fc, fcp);
 
 		fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
 		if (fle) {
@@ -215,7 +217,7 @@ void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
 			fle->dir = dir;
 			memcpy(&fle->key, key, sizeof(*key));
 			fle->object = NULL;
-			flow_count(cpu)++;
+			fcp->hash_count++;
 		}
 	}
 
@@ -249,14 +251,15 @@ nocache:
 static void flow_cache_flush_tasklet(unsigned long data)
 {
 	struct flow_flush_info *info = (void *)data;
+	struct flow_cache *fc = info->cache;
+	struct flow_cache_percpu *fcp;
 	int i;
-	int cpu;
 
-	cpu = smp_processor_id();
-	for (i = 0; i < flow_hash_size; i++) {
+	fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
+	for (i = 0; i < flow_cache_hash_size(fc); i++) {
 		struct flow_cache_entry *fle;
 
-		fle = flow_table(cpu)[i];
+		fle = fcp->hash_table[i];
 		for (; fle; fle = fle->next) {
 			unsigned genid = atomic_read(&flow_cache_genid);
 
@@ -272,7 +275,6 @@ static void flow_cache_flush_tasklet(unsigned long data)
 		complete(&info->completion);
 }
 
-static void flow_cache_flush_per_cpu(void *) __attribute__((__unused__));
 static void flow_cache_flush_per_cpu(void *data)
 {
 	struct flow_flush_info *info = data;
@@ -280,8 +282,7 @@ static void flow_cache_flush_per_cpu(void *data)
 	struct tasklet_struct *tasklet;
 
 	cpu = smp_processor_id();
-
-	tasklet = flow_flush_tasklet(cpu);
+	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
 	tasklet->data = (unsigned long)info;
 	tasklet_schedule(tasklet);
 }
@@ -294,6 +295,7 @@ void flow_cache_flush(void)
 	/* Don't want cpus going down or up during this. */
 	get_online_cpus();
 	mutex_lock(&flow_flush_sem);
+	info.cache = &flow_cache_global;
 	atomic_set(&info.cpuleft, num_online_cpus());
 	init_completion(&info.completion);
 
@@ -307,62 +309,75 @@ void flow_cache_flush(void)
 	put_online_cpus();
 }
 
-static void __init flow_cache_cpu_prepare(int cpu)
+static void __init flow_cache_cpu_prepare(struct flow_cache *fc,
+					  struct flow_cache_percpu *fcp)
 {
-	struct tasklet_struct *tasklet;
-	unsigned long order;
-
-	for (order = 0;
-	     (PAGE_SIZE << order) <
-		     (sizeof(struct flow_cache_entry *)*flow_hash_size);
-	     order++)
-		/* NOTHING */;
-
-	flow_table(cpu) = (struct flow_cache_entry **)
-		__get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
-	if (!flow_table(cpu))
-		panic("NET: failed to allocate flow cache order %lu\n", order);
-
-	flow_hash_rnd_recalc(cpu) = 1;
-	flow_count(cpu) = 0;
-
-	tasklet = flow_flush_tasklet(cpu);
-	tasklet_init(tasklet, flow_cache_flush_tasklet, 0);
+	fcp->hash_table = (struct flow_cache_entry **)
+		__get_free_pages(GFP_KERNEL|__GFP_ZERO, fc->order);
+	if (!fcp->hash_table)
+		panic("NET: failed to allocate flow cache order %lu\n", fc->order);
+
+	fcp->hash_rnd_recalc = 1;
+	fcp->hash_count = 0;
+	tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
 }
 
 static int flow_cache_cpu(struct notifier_block *nfb,
 			  unsigned long action,
 			  void *hcpu)
 {
+	struct flow_cache *fc = container_of(nfb, struct flow_cache, hotcpu_notifier);
+	int cpu = (unsigned long) hcpu;
+	struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
+
 	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
-		__flow_cache_shrink((unsigned long)hcpu, 0);
+		__flow_cache_shrink(fc, fcp, 0);
 	return NOTIFY_OK;
 }
 
-static int __init flow_cache_init(void)
+static int flow_cache_init(struct flow_cache *fc)
 {
+	unsigned long order;
 	int i;
 
-	flow_cachep = kmem_cache_create("flow_cache",
-					sizeof(struct flow_cache_entry),
-					0, SLAB_PANIC,
-					NULL);
-	flow_hash_shift = 10;
-	flow_lwm = 2 * flow_hash_size;
-	flow_hwm = 4 * flow_hash_size;
+	fc->hash_shift = 10;
+	fc->low_watermark = 2 * flow_cache_hash_size(fc);
+	fc->high_watermark = 4 * flow_cache_hash_size(fc);
+
+	for (order = 0;
+	     (PAGE_SIZE << order) <
+		     (sizeof(struct flow_cache_entry *)*flow_cache_hash_size(fc));
+	     order++)
+		/* NOTHING */;
+	fc->order = order;
+	fc->percpu = alloc_percpu(struct flow_cache_percpu);
 
-	setup_timer(&flow_hash_rnd_timer, flow_cache_new_hashrnd, 0);
-	flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
-	add_timer(&flow_hash_rnd_timer);
+	setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
+		    (unsigned long) fc);
+	fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+	add_timer(&fc->rnd_timer);
 
 	for_each_possible_cpu(i)
-		flow_cache_cpu_prepare(i);
+		flow_cache_cpu_prepare(fc, per_cpu_ptr(fc->percpu, i));
+
+	fc->hotcpu_notifier = (struct notifier_block){
+		.notifier_call = flow_cache_cpu,
+	};
+	register_hotcpu_notifier(&fc->hotcpu_notifier);
 
-	hotcpu_notifier(flow_cache_cpu, 0);
 	return 0;
 }
 
-module_init(flow_cache_init);
+static int __init flow_cache_init_global(void)
+{
+	flow_cachep = kmem_cache_create("flow_cache",
+					sizeof(struct flow_cache_entry),
+					0, SLAB_PANIC, NULL);
+
+	return flow_cache_init(&flow_cache_global);
+}
+
+module_init(flow_cache_init_global);
 
 EXPORT_SYMBOL(flow_cache_genid);
 EXPORT_SYMBOL(flow_cache_lookup);
-- 
1.6.3.3

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