linux/net/core/flow.c
Timo Teräs 8e4795605d flow: delayed deletion of flow cache entries
Speed up lookups by freeing flow cache entries later. After
virtualizing flow cache entry operations, the flow cache may now
end up calling policy or bundle destructor which can be slowish.

As gc_list is more effective with double linked list, the flow cache
is converted to use common hlist and list macroes where appropriate.

Signed-off-by: Timo Teras <timo.teras@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-04-07 03:43:20 -07:00

430 lines
10 KiB
C

/* flow.c: Generic flow cache.
*
* Copyright (C) 2003 Alexey N. Kuznetsov (kuznet@ms2.inr.ac.ru)
* Copyright (C) 2003 David S. Miller (davem@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/completion.h>
#include <linux/percpu.h>
#include <linux/bitops.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/mutex.h>
#include <net/flow.h>
#include <asm/atomic.h>
#include <linux/security.h>
struct flow_cache_entry {
union {
struct hlist_node hlist;
struct list_head gc_list;
} u;
u16 family;
u8 dir;
u32 genid;
struct flowi key;
struct flow_cache_object *object;
};
struct flow_cache_percpu {
struct hlist_head *hash_table;
int hash_count;
u32 hash_rnd;
int hash_rnd_recalc;
struct tasklet_struct flush_tasklet;
};
struct flow_flush_info {
struct flow_cache *cache;
atomic_t cpuleft;
struct completion completion;
};
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;
static DEFINE_SPINLOCK(flow_cache_gc_lock);
static LIST_HEAD(flow_cache_gc_list);
#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)
per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
add_timer(&fc->rnd_timer);
}
static int flow_entry_valid(struct flow_cache_entry *fle)
{
if (atomic_read(&flow_cache_genid) != fle->genid)
return 0;
if (fle->object && !fle->object->ops->check(fle->object))
return 0;
return 1;
}
static void flow_entry_kill(struct flow_cache_entry *fle)
{
if (fle->object)
fle->object->ops->delete(fle->object);
kmem_cache_free(flow_cachep, fle);
}
static void flow_cache_gc_task(struct work_struct *work)
{
struct list_head gc_list;
struct flow_cache_entry *fce, *n;
INIT_LIST_HEAD(&gc_list);
spin_lock_bh(&flow_cache_gc_lock);
list_splice_tail_init(&flow_cache_gc_list, &gc_list);
spin_unlock_bh(&flow_cache_gc_lock);
list_for_each_entry_safe(fce, n, &gc_list, u.gc_list)
flow_entry_kill(fce);
}
static DECLARE_WORK(flow_cache_gc_work, flow_cache_gc_task);
static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
int deleted, struct list_head *gc_list)
{
if (deleted) {
fcp->hash_count -= deleted;
spin_lock_bh(&flow_cache_gc_lock);
list_splice_tail(gc_list, &flow_cache_gc_list);
spin_unlock_bh(&flow_cache_gc_lock);
schedule_work(&flow_cache_gc_work);
}
}
static void __flow_cache_shrink(struct flow_cache *fc,
struct flow_cache_percpu *fcp,
int shrink_to)
{
struct flow_cache_entry *fle;
struct hlist_node *entry, *tmp;
LIST_HEAD(gc_list);
int i, deleted = 0;
for (i = 0; i < flow_cache_hash_size(fc); i++) {
int saved = 0;
hlist_for_each_entry_safe(fle, entry, tmp,
&fcp->hash_table[i], u.hlist) {
if (saved < shrink_to &&
flow_entry_valid(fle)) {
saved++;
} else {
deleted++;
hlist_del(&fle->u.hlist);
list_add_tail(&fle->u.gc_list, &gc_list);
}
}
}
flow_cache_queue_garbage(fcp, deleted, &gc_list);
}
static void flow_cache_shrink(struct flow_cache *fc,
struct flow_cache_percpu *fcp)
{
int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
__flow_cache_shrink(fc, fcp, shrink_to);
}
static void flow_new_hash_rnd(struct flow_cache *fc,
struct flow_cache_percpu *fcp)
{
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 flow_cache *fc,
struct flow_cache_percpu *fcp,
struct flowi *key)
{
u32 *k = (u32 *) key;
return (jhash2(k, (sizeof(*key) / sizeof(u32)), fcp->hash_rnd)
& (flow_cache_hash_size(fc) - 1));
}
#if (BITS_PER_LONG == 64)
typedef u64 flow_compare_t;
#else
typedef u32 flow_compare_t;
#endif
/* I hear what you're saying, use memcmp. But memcmp cannot make
* important assumptions that we can here, such as alignment and
* constant size.
*/
static int flow_key_compare(struct flowi *key1, struct flowi *key2)
{
flow_compare_t *k1, *k1_lim, *k2;
const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
BUILD_BUG_ON(sizeof(struct flowi) % sizeof(flow_compare_t));
k1 = (flow_compare_t *) key1;
k1_lim = k1 + n_elem;
k2 = (flow_compare_t *) key2;
do {
if (*k1++ != *k2++)
return 1;
} while (k1 < k1_lim);
return 0;
}
struct flow_cache_object *
flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
flow_resolve_t resolver, void *ctx)
{
struct flow_cache *fc = &flow_cache_global;
struct flow_cache_percpu *fcp;
struct flow_cache_entry *fle, *tfle;
struct hlist_node *entry;
struct flow_cache_object *flo;
unsigned int hash;
local_bh_disable();
fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
fle = NULL;
flo = NULL;
/* Packet really early in init? Making flow_cache_init a
* pre-smp initcall would solve this. --RR */
if (!fcp->hash_table)
goto nocache;
if (fcp->hash_rnd_recalc)
flow_new_hash_rnd(fc, fcp);
hash = flow_hash_code(fc, fcp, key);
hlist_for_each_entry(tfle, entry, &fcp->hash_table[hash], u.hlist) {
if (tfle->family == family &&
tfle->dir == dir &&
flow_key_compare(key, &tfle->key) == 0) {
fle = tfle;
break;
}
}
if (unlikely(!fle)) {
if (fcp->hash_count > fc->high_watermark)
flow_cache_shrink(fc, fcp);
fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
if (fle) {
fle->family = family;
fle->dir = dir;
memcpy(&fle->key, key, sizeof(*key));
fle->object = NULL;
hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
fcp->hash_count++;
}
} else if (likely(fle->genid == atomic_read(&flow_cache_genid))) {
flo = fle->object;
if (!flo)
goto ret_object;
flo = flo->ops->get(flo);
if (flo)
goto ret_object;
} else if (fle->object) {
flo = fle->object;
flo->ops->delete(flo);
fle->object = NULL;
}
nocache:
flo = NULL;
if (fle) {
flo = fle->object;
fle->object = NULL;
}
flo = resolver(net, key, family, dir, flo, ctx);
if (fle) {
fle->genid = atomic_read(&flow_cache_genid);
if (!IS_ERR(flo))
fle->object = flo;
else
fle->genid--;
} else {
if (flo && !IS_ERR(flo))
flo->ops->delete(flo);
}
ret_object:
local_bh_enable();
return flo;
}
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;
struct flow_cache_entry *fle;
struct hlist_node *entry, *tmp;
LIST_HEAD(gc_list);
int i, deleted = 0;
fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
for (i = 0; i < flow_cache_hash_size(fc); i++) {
hlist_for_each_entry_safe(fle, entry, tmp,
&fcp->hash_table[i], u.hlist) {
if (flow_entry_valid(fle))
continue;
deleted++;
hlist_del(&fle->u.hlist);
list_add_tail(&fle->u.gc_list, &gc_list);
}
}
flow_cache_queue_garbage(fcp, deleted, &gc_list);
if (atomic_dec_and_test(&info->cpuleft))
complete(&info->completion);
}
static void flow_cache_flush_per_cpu(void *data)
{
struct flow_flush_info *info = data;
int cpu;
struct tasklet_struct *tasklet;
cpu = smp_processor_id();
tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
tasklet->data = (unsigned long)info;
tasklet_schedule(tasklet);
}
void flow_cache_flush(void)
{
struct flow_flush_info info;
static DEFINE_MUTEX(flow_flush_sem);
/* 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);
local_bh_disable();
smp_call_function(flow_cache_flush_per_cpu, &info, 0);
flow_cache_flush_tasklet((unsigned long)&info);
local_bh_enable();
wait_for_completion(&info.completion);
mutex_unlock(&flow_flush_sem);
put_online_cpus();
}
static void __init flow_cache_cpu_prepare(struct flow_cache *fc,
struct flow_cache_percpu *fcp)
{
fcp->hash_table = (struct hlist_head *)
__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(fc, fcp, 0);
return NOTIFY_OK;
}
static int flow_cache_init(struct flow_cache *fc)
{
unsigned long order;
int i;
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 hlist_head)*flow_cache_hash_size(fc));
order++)
/* NOTHING */;
fc->order = order;
fc->percpu = alloc_percpu(struct flow_cache_percpu);
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(fc, per_cpu_ptr(fc->percpu, i));
fc->hotcpu_notifier = (struct notifier_block){
.notifier_call = flow_cache_cpu,
};
register_hotcpu_notifier(&fc->hotcpu_notifier);
return 0;
}
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);