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flow: structurize flow cache
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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 <[email protected]>
Acked-by: Herbert Xu <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@fabled @davem330
fabled authored and davem330 committed Apr 2, 2010
1 parent ea2dea9 commit d7997fe
Showing 1 changed file with 119 additions and 104 deletions.
223 changes: 119 additions & 104 deletions net/core/flow.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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 &&
Expand All @@ -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) {
Expand All @@ -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++;
}
}

Expand Down Expand Up @@ -249,14 +251,15 @@ void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
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);

Expand All @@ -272,16 +275,14 @@ 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;
int cpu;
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);
}
Expand All @@ -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);

Expand All @@ -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);

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