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skbmgr.cc
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skbmgr.cc
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// -*- c-basic-offset: 2; related-file-name: "../include/click/skbmgr.hh" -*-
/*
* skbmgr.cc -- Linux kernel module sk_buff manager
* Benjie Chen, Eddie Kohler
*
* Copyright (c) 2001 Massachusetts Institute of Technology
* Copyright (c) 2001 International Computer Science Institute
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, subject to the conditions
* listed in the Click LICENSE file. These conditions include: you must
* preserve this copyright notice, and you cannot mention the copyright
* holders in advertising related to the Software without their permission.
* The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
* notice is a summary of the Click LICENSE file; the license in that file is
* legally binding.
*/
#include <click/config.h>
#include <click/glue.hh>
#include <click/atomic.hh>
#include <click/sync.hh>
#include <click/skbmgr.hh>
#include <click/cxxprotect.h>
CLICK_CXX_PROTECT
#include <asm/bitops.h>
#include <asm/atomic.h>
#include <linux/netdevice.h>
#include <net/dst.h>
#include <linux/if_packet.h>
CLICK_CXX_UNPROTECT
#include <click/cxxunprotect.h>
#define DEBUG_SKBMGR 1
class RecycledSkbBucket { public:
static const int SIZE = 62;
void initialize();
void cleanup();
bool empty() const { return _head == _tail; }
unsigned size() const;
int enq(struct sk_buff *); // returns -1 if not enqueued
struct sk_buff *deq();
private:
int _head;
int _tail;
struct sk_buff *_skbs[SIZE];
static int next_i(int i) { return (i == SIZE - 1 ? 0 : i + 1); }
friend class RecycledSkbPool;
};
class RecycledSkbPool { public:
static const int NBUCKETS = 2;
void initialize();
void cleanup();
RecycledSkbBucket &bucket(int);
static int size_to_lower_bucket(unsigned);
static int size_to_higher_bucket(unsigned);
static unsigned size_to_lower_bucket_size(unsigned);
static unsigned size_to_higher_bucket_size(unsigned);
private:
RecycledSkbBucket _buckets[NBUCKETS];
unsigned long _lock;
#if __MTCLICK__
int _last_producer;
atomic_uint32_t _consumers;
#else
int _pad2[2];
#endif
#if DEBUG_SKBMGR
int _allocated;
int _freed;
int _recycle_freed;
int _recycle_allocated;
int _pad[1];
#else
int _pad[5];
#endif
inline void lock();
inline void unlock();
struct sk_buff *allocate(unsigned headroom, unsigned size, int, int *);
void recycle(struct sk_buff *);
#if __MTCLICK__
static int find_producer(int, int);
#endif
friend struct sk_buff *skbmgr_allocate_skbs(unsigned, unsigned, int *);
friend void skbmgr_recycle_skbs(struct sk_buff *);
};
void
RecycledSkbBucket::initialize()
{
_head = _tail = 0;
memset(_skbs, 0, sizeof(_skbs));
}
void
RecycledSkbBucket::cleanup()
{
for (int i = _head; i != _tail; i = next_i(i))
kfree_skb(_skbs[i]);
_head = _tail = 0;
}
inline unsigned
RecycledSkbBucket::size() const
{
return (_head <= _tail ? _tail - _head : _tail + SIZE - _head);
}
inline int
RecycledSkbBucket::enq(struct sk_buff *skb)
{
int n = next_i(_tail);
if (n == _head)
return -1;
_skbs[_tail] = skb;
_tail = n;
return 0;
}
inline struct sk_buff *
RecycledSkbBucket::deq()
{
if (_head == _tail)
return 0;
else {
struct sk_buff *skb = _skbs[_head];
_head = next_i(_head);
return skb;
}
}
inline void
RecycledSkbPool::lock()
{
while (test_and_set_bit(0, &_lock)) {
while (_lock)
click_relax_fence();
}
}
inline void
RecycledSkbPool::unlock()
{
clear_bit(0, &_lock);
}
void
RecycledSkbPool::initialize()
{
_lock = 0;
for (int i = 0; i < NBUCKETS; i++)
_buckets[i].initialize();
#if __MTCLICK__
_last_producer = -1;
_consumers = 0;
#endif
#if DEBUG_SKBMGR
_recycle_freed = 0;
_freed = 0;
_recycle_allocated = 0;
_allocated = 0;
#endif
}
void
RecycledSkbPool::cleanup()
{
lock();
for (int i = 0; i < NBUCKETS; i++)
_buckets[i].cleanup();
#if __MTCLICK__
_last_producer = -1;
_consumers = 0;
#endif
#if DEBUG_SKBMGR
if (_freed > 0 || _allocated > 0)
printk("poll %p: %d/%d freed, %d/%d allocated\n", this,
_freed, _recycle_freed, _allocated, _recycle_allocated);
#endif
unlock();
}
inline RecycledSkbBucket &
RecycledSkbPool::bucket(int i)
{
assert((unsigned)i < NBUCKETS);
return _buckets[i];
}
inline int
RecycledSkbPool::size_to_lower_bucket(unsigned size)
{
if (size >= 1800) return 1;
if (size >= 500) return 0;
return -1;
}
inline int
RecycledSkbPool::size_to_higher_bucket(unsigned size)
{
if (size <= 500) return 0;
if (size <= 1800) return 1;
return -1;
}
inline unsigned
RecycledSkbPool::size_to_lower_bucket_size(unsigned size)
{
if (size >= 1800) return 1800;
if (size >= 500) return 500;
return size;
}
inline unsigned
RecycledSkbPool::size_to_higher_bucket_size(unsigned size)
{
if (size <= 500) return 500;
if (size <= 1800) return 1800;
return size;
}
#if __MTCLICK__
static RecycledSkbPool pool[NR_CPUS];
#else
static RecycledSkbPool pool;
#endif
#define SKBMGR_DEF_TAILSZ 64
#define SKBMGR_DEF_HEADSZ 64 // must be divisible by 4
#if __MTCLICK__
inline int
RecycledSkbPool::find_producer(int cpu, int bucket)
{
int max_skbs = 0;
int max_pool = -1;
int i;
if (pool[cpu]._last_producer >= 0)
pool[pool[cpu]._last_producer]._consumers--;
for (i = 0; i < num_possible_cpus(); i++) {
int s = pool[i].bucket(bucket).size();
int c = pool[i]._consumers + 1;
if (c < 1) c = 1;
s = s/c;
if (s > max_skbs) {
max_skbs = s;
max_pool = i;
}
}
pool[cpu]._last_producer = max_pool;
if (pool[cpu]._last_producer >= 0)
pool[pool[cpu]._last_producer]._consumers++;
return pool[cpu]._last_producer;
}
#endif
void
RecycledSkbPool::recycle(struct sk_buff *skbs)
{
while (skbs) {
struct sk_buff *skb = skbs;
skbs = skbs->next;
#if HAVE_CLICK_SKB_RECYCLE || HAVE_SKB_RECYCLE_CHECK
// where should sk_buff go?
# if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 24)
unsigned char *skb_end = skb_end_pointer(skb);
# else
unsigned char *skb_end = skb->end;
# endif
int bucket = size_to_lower_bucket(skb_end - skb->head);
// try to put in that bucket
if (bucket >= 0) {
lock();
int tail = _buckets[bucket]._tail;
int next = _buckets[bucket].next_i(tail);
if (next != _buckets[bucket]._head) {
#if HAVE_CLICK_SKB_RECYCLE
// Note: skb_recycle_fast will free the skb if it cannot recycle it
if ((skb = skb_recycle(skb))) {
#elif HAVE_SKB_RECYCLE_CHECK
if (skb_recycle_check(skb, size_to_lower_bucket_size(skb_end - skb->head))) {
#endif
_buckets[bucket]._skbs[tail] = skb;
_buckets[bucket]._tail = next;
skb = 0;
# if DEBUG_SKBMGR
_recycle_freed++;
# endif
}
}
unlock();
}
#endif
// if not taken care of, then free it
if (skb) {
#if DEBUG_SKBMGR
_freed++;
#endif
kfree_skb(skb);
}
}
}
struct sk_buff *
RecycledSkbPool::allocate(unsigned headroom, unsigned size, int want, int *store_got)
{
int bucket = size_to_higher_bucket(headroom + size);
struct sk_buff *head;
struct sk_buff **prev = &head;
int got = 0;
if (bucket >= 0) {
lock();
RecycledSkbBucket &buck = _buckets[bucket];
while (got < want && !buck.empty()) {
struct sk_buff *skb = _buckets[bucket].deq();
#if DEBUG_SKBMGR
_recycle_allocated++;
#endif
skb_reserve(skb, headroom);
*prev = skb;
prev = &skb->next;
got++;
}
unlock();
}
size = size_to_higher_bucket_size(headroom + size);
while (got < want) {
struct sk_buff *skb = alloc_skb(size, GFP_ATOMIC);
#if DEBUG_SKBMGR
_allocated++;
#endif
if (!skb) {
printk(KERN_ALERT "oops, kernel could not allocate memory for skbuff\n");
break;
}
skb_reserve(skb, headroom);
*prev = skb;
prev = &skb->next;
got++;
}
*prev = 0;
*store_got = got;
return head;
}
void
skbmgr_init()
{
#if __MTCLICK__
for (int i = 0; i < NR_CPUS; i++)
pool[i].initialize();
#else
pool.initialize();
#endif
}
void
skbmgr_cleanup()
{
#if __MTCLICK__
for (int i = 0; i < NR_CPUS; i++)
pool[i].cleanup();
#else
pool.cleanup();
#endif
}
struct sk_buff *
skbmgr_allocate_skbs(unsigned headroom, unsigned size, int *want)
{
if (headroom == 0)
headroom = SKBMGR_DEF_HEADSZ;
size += SKBMGR_DEF_TAILSZ;
#if __MTCLICK__
click_processor_t cpu = click_get_processor();
int producer = cpu;
int bucket = RecycledSkbPool::size_to_higher_bucket(headroom + size);
int w = *want;
if (pool[producer].bucket(bucket).size() < w) {
if (pool[cpu]._last_producer < 0 ||
pool[pool[cpu]._last_producer].bucket(bucket).size() < w)
RecycledSkbPool::find_producer(cpu, bucket);
if (pool[cpu]._last_producer >= 0)
producer = pool[cpu]._last_producer;
}
sk_buff *skb = pool[producer].allocate(headroom, size, w, want);
click_put_processor();
return skb;
#else
return pool.allocate(headroom, size, *want, want);
#endif
}
void
skbmgr_recycle_skbs(struct sk_buff *skbs)
{
#if __MTCLICK__
click_processor_t cpu = click_get_processor();
pool[cpu].recycle(skbs);
click_put_processor();
#else
pool.recycle(skbs);
#endif
}