fq: add fair queuing framework
This works on the same implementation principle as codel*.h, i.e. there's a generic header with structures and macros and a implementation header carrying function definitions to include in given, e.g. driver or module. The fairness logic comes from net/sched/sch_fq_codel.c but is generalized so it is more flexible and easier to re-use. Signed-off-by: Michal Kazior <michal.kazior@tieto.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michal Kazior
David S. Miller
Родитель
05d82c4250
Коммит
557fc4a098
|
|
@ -0,0 +1,95 @@
|
|||
/*
|
||||
* Copyright (c) 2016 Qualcomm Atheros, Inc
|
||||
*
|
||||
* GPL v2
|
||||
*
|
||||
* Based on net/sched/sch_fq_codel.c
|
||||
*/
|
||||
#ifndef __NET_SCHED_FQ_H
|
||||
#define __NET_SCHED_FQ_H
|
||||
|
||||
struct fq_tin;
|
||||
|
||||
/**
|
||||
* struct fq_flow - per traffic flow queue
|
||||
*
|
||||
* @tin: owner of this flow. Used to manage collisions, i.e. when a packet
|
||||
* hashes to an index which points to a flow that is already owned by a
|
||||
* different tin the packet is destined to. In such case the implementer
|
||||
* must provide a fallback flow
|
||||
* @flowchain: can be linked to fq_tin's new_flows or old_flows. Used for DRR++
|
||||
* (deficit round robin) based round robin queuing similar to the one
|
||||
* found in net/sched/sch_fq_codel.c
|
||||
* @backlogchain: can be linked to other fq_flow and fq. Used to keep track of
|
||||
* fat flows and efficient head-dropping if packet limit is reached
|
||||
* @queue: sk_buff queue to hold packets
|
||||
* @backlog: number of bytes pending in the queue. The number of packets can be
|
||||
* found in @queue.qlen
|
||||
* @deficit: used for DRR++
|
||||
*/
|
||||
struct fq_flow {
|
||||
struct fq_tin *tin;
|
||||
struct list_head flowchain;
|
||||
struct list_head backlogchain;
|
||||
struct sk_buff_head queue;
|
||||
u32 backlog;
|
||||
int deficit;
|
||||
};
|
||||
|
||||
/**
|
||||
* struct fq_tin - a logical container of fq_flows
|
||||
*
|
||||
* Used to group fq_flows into a logical aggregate. DRR++ scheme is used to
|
||||
* pull interleaved packets out of the associated flows.
|
||||
*
|
||||
* @new_flows: linked list of fq_flow
|
||||
* @old_flows: linked list of fq_flow
|
||||
*/
|
||||
struct fq_tin {
|
||||
struct list_head new_flows;
|
||||
struct list_head old_flows;
|
||||
u32 backlog_bytes;
|
||||
u32 backlog_packets;
|
||||
u32 overlimit;
|
||||
u32 collisions;
|
||||
u32 flows;
|
||||
u32 tx_bytes;
|
||||
u32 tx_packets;
|
||||
};
|
||||
|
||||
/**
|
||||
* struct fq - main container for fair queuing purposes
|
||||
*
|
||||
* @backlogs: linked to fq_flows. Used to maintain fat flows for efficient
|
||||
* head-dropping when @backlog reaches @limit
|
||||
* @limit: max number of packets that can be queued across all flows
|
||||
* @backlog: number of packets queued across all flows
|
||||
*/
|
||||
struct fq {
|
||||
struct fq_flow *flows;
|
||||
struct list_head backlogs;
|
||||
spinlock_t lock;
|
||||
u32 flows_cnt;
|
||||
u32 perturbation;
|
||||
u32 limit;
|
||||
u32 quantum;
|
||||
u32 backlog;
|
||||
u32 overlimit;
|
||||
u32 collisions;
|
||||
};
|
||||
|
||||
typedef struct sk_buff *fq_tin_dequeue_t(struct fq *,
|
||||
struct fq_tin *,
|
||||
struct fq_flow *flow);
|
||||
|
||||
typedef void fq_skb_free_t(struct fq *,
|
||||
struct fq_tin *,
|
||||
struct fq_flow *,
|
||||
struct sk_buff *);
|
||||
|
||||
typedef struct fq_flow *fq_flow_get_default_t(struct fq *,
|
||||
struct fq_tin *,
|
||||
int idx,
|
||||
struct sk_buff *);
|
||||
|
||||
#endif
|
||||
|
|
@ -0,0 +1,269 @@
|
|||
/*
|
||||
* Copyright (c) 2016 Qualcomm Atheros, Inc
|
||||
*
|
||||
* GPL v2
|
||||
*
|
||||
* Based on net/sched/sch_fq_codel.c
|
||||
*/
|
||||
#ifndef __NET_SCHED_FQ_IMPL_H
|
||||
#define __NET_SCHED_FQ_IMPL_H
|
||||
|
||||
#include <net/fq.h>
|
||||
|
||||
/* functions that are embedded into includer */
|
||||
|
||||
static struct sk_buff *fq_flow_dequeue(struct fq *fq,
|
||||
struct fq_flow *flow)
|
||||
{
|
||||
struct fq_tin *tin = flow->tin;
|
||||
struct fq_flow *i;
|
||||
struct sk_buff *skb;
|
||||
|
||||
lockdep_assert_held(&fq->lock);
|
||||
|
||||
skb = __skb_dequeue(&flow->queue);
|
||||
if (!skb)
|
||||
return NULL;
|
||||
|
||||
tin->backlog_bytes -= skb->len;
|
||||
tin->backlog_packets--;
|
||||
flow->backlog -= skb->len;
|
||||
fq->backlog--;
|
||||
|
||||
if (flow->backlog == 0) {
|
||||
list_del_init(&flow->backlogchain);
|
||||
} else {
|
||||
i = flow;
|
||||
|
||||
list_for_each_entry_continue(i, &fq->backlogs, backlogchain)
|
||||
if (i->backlog < flow->backlog)
|
||||
break;
|
||||
|
||||
list_move_tail(&flow->backlogchain,
|
||||
&i->backlogchain);
|
||||
}
|
||||
|
||||
return skb;
|
||||
}
|
||||
|
||||
static struct sk_buff *fq_tin_dequeue(struct fq *fq,
|
||||
struct fq_tin *tin,
|
||||
fq_tin_dequeue_t dequeue_func)
|
||||
{
|
||||
struct fq_flow *flow;
|
||||
struct list_head *head;
|
||||
struct sk_buff *skb;
|
||||
|
||||
lockdep_assert_held(&fq->lock);
|
||||
|
||||
begin:
|
||||
head = &tin->new_flows;
|
||||
if (list_empty(head)) {
|
||||
head = &tin->old_flows;
|
||||
if (list_empty(head))
|
||||
return NULL;
|
||||
}
|
||||
|
||||
flow = list_first_entry(head, struct fq_flow, flowchain);
|
||||
|
||||
if (flow->deficit <= 0) {
|
||||
flow->deficit += fq->quantum;
|
||||
list_move_tail(&flow->flowchain,
|
||||
&tin->old_flows);
|
||||
goto begin;
|
||||
}
|
||||
|
||||
skb = dequeue_func(fq, tin, flow);
|
||||
if (!skb) {
|
||||
/* force a pass through old_flows to prevent starvation */
|
||||
if ((head == &tin->new_flows) &&
|
||||
!list_empty(&tin->old_flows)) {
|
||||
list_move_tail(&flow->flowchain, &tin->old_flows);
|
||||
} else {
|
||||
list_del_init(&flow->flowchain);
|
||||
flow->tin = NULL;
|
||||
}
|
||||
goto begin;
|
||||
}
|
||||
|
||||
flow->deficit -= skb->len;
|
||||
tin->tx_bytes += skb->len;
|
||||
tin->tx_packets++;
|
||||
|
||||
return skb;
|
||||
}
|
||||
|
||||
static struct fq_flow *fq_flow_classify(struct fq *fq,
|
||||
struct fq_tin *tin,
|
||||
struct sk_buff *skb,
|
||||
fq_flow_get_default_t get_default_func)
|
||||
{
|
||||
struct fq_flow *flow;
|
||||
u32 hash;
|
||||
u32 idx;
|
||||
|
||||
lockdep_assert_held(&fq->lock);
|
||||
|
||||
hash = skb_get_hash_perturb(skb, fq->perturbation);
|
||||
idx = reciprocal_scale(hash, fq->flows_cnt);
|
||||
flow = &fq->flows[idx];
|
||||
|
||||
if (flow->tin && flow->tin != tin) {
|
||||
flow = get_default_func(fq, tin, idx, skb);
|
||||
tin->collisions++;
|
||||
fq->collisions++;
|
||||
}
|
||||
|
||||
if (!flow->tin)
|
||||
tin->flows++;
|
||||
|
||||
return flow;
|
||||
}
|
||||
|
||||
static void fq_tin_enqueue(struct fq *fq,
|
||||
struct fq_tin *tin,
|
||||
struct sk_buff *skb,
|
||||
fq_skb_free_t free_func,
|
||||
fq_flow_get_default_t get_default_func)
|
||||
{
|
||||
struct fq_flow *flow;
|
||||
struct fq_flow *i;
|
||||
|
||||
lockdep_assert_held(&fq->lock);
|
||||
|
||||
flow = fq_flow_classify(fq, tin, skb, get_default_func);
|
||||
|
||||
flow->tin = tin;
|
||||
flow->backlog += skb->len;
|
||||
tin->backlog_bytes += skb->len;
|
||||
tin->backlog_packets++;
|
||||
fq->backlog++;
|
||||
|
||||
if (list_empty(&flow->backlogchain))
|
||||
list_add_tail(&flow->backlogchain, &fq->backlogs);
|
||||
|
||||
i = flow;
|
||||
list_for_each_entry_continue_reverse(i, &fq->backlogs,
|
||||
backlogchain)
|
||||
if (i->backlog > flow->backlog)
|
||||
break;
|
||||
|
||||
list_move(&flow->backlogchain, &i->backlogchain);
|
||||
|
||||
if (list_empty(&flow->flowchain)) {
|
||||
flow->deficit = fq->quantum;
|
||||
list_add_tail(&flow->flowchain,
|
||||
&tin->new_flows);
|
||||
}
|
||||
|
||||
__skb_queue_tail(&flow->queue, skb);
|
||||
|
||||
if (fq->backlog > fq->limit) {
|
||||
flow = list_first_entry_or_null(&fq->backlogs,
|
||||
struct fq_flow,
|
||||
backlogchain);
|
||||
if (!flow)
|
||||
return;
|
||||
|
||||
skb = fq_flow_dequeue(fq, flow);
|
||||
if (!skb)
|
||||
return;
|
||||
|
||||
free_func(fq, flow->tin, flow, skb);
|
||||
|
||||
flow->tin->overlimit++;
|
||||
fq->overlimit++;
|
||||
}
|
||||
}
|
||||
|
||||
static void fq_flow_reset(struct fq *fq,
|
||||
struct fq_flow *flow,
|
||||
fq_skb_free_t free_func)
|
||||
{
|
||||
struct sk_buff *skb;
|
||||
|
||||
while ((skb = fq_flow_dequeue(fq, flow)))
|
||||
free_func(fq, flow->tin, flow, skb);
|
||||
|
||||
if (!list_empty(&flow->flowchain))
|
||||
list_del_init(&flow->flowchain);
|
||||
|
||||
if (!list_empty(&flow->backlogchain))
|
||||
list_del_init(&flow->backlogchain);
|
||||
|
||||
flow->tin = NULL;
|
||||
|
||||
WARN_ON_ONCE(flow->backlog);
|
||||
}
|
||||
|
||||
static void fq_tin_reset(struct fq *fq,
|
||||
struct fq_tin *tin,
|
||||
fq_skb_free_t free_func)
|
||||
{
|
||||
struct list_head *head;
|
||||
struct fq_flow *flow;
|
||||
|
||||
for (;;) {
|
||||
head = &tin->new_flows;
|
||||
if (list_empty(head)) {
|
||||
head = &tin->old_flows;
|
||||
if (list_empty(head))
|
||||
break;
|
||||
}
|
||||
|
||||
flow = list_first_entry(head, struct fq_flow, flowchain);
|
||||
fq_flow_reset(fq, flow, free_func);
|
||||
}
|
||||
|
||||
WARN_ON_ONCE(tin->backlog_bytes);
|
||||
WARN_ON_ONCE(tin->backlog_packets);
|
||||
}
|
||||
|
||||
static void fq_flow_init(struct fq_flow *flow)
|
||||
{
|
||||
INIT_LIST_HEAD(&flow->flowchain);
|
||||
INIT_LIST_HEAD(&flow->backlogchain);
|
||||
__skb_queue_head_init(&flow->queue);
|
||||
}
|
||||
|
||||
static void fq_tin_init(struct fq_tin *tin)
|
||||
{
|
||||
INIT_LIST_HEAD(&tin->new_flows);
|
||||
INIT_LIST_HEAD(&tin->old_flows);
|
||||
}
|
||||
|
||||
static int fq_init(struct fq *fq, int flows_cnt)
|
||||
{
|
||||
int i;
|
||||
|
||||
memset(fq, 0, sizeof(fq[0]));
|
||||
INIT_LIST_HEAD(&fq->backlogs);
|
||||
spin_lock_init(&fq->lock);
|
||||
fq->flows_cnt = max_t(u32, flows_cnt, 1);
|
||||
fq->perturbation = prandom_u32();
|
||||
fq->quantum = 300;
|
||||
fq->limit = 8192;
|
||||
|
||||
fq->flows = kcalloc(fq->flows_cnt, sizeof(fq->flows[0]), GFP_KERNEL);
|
||||
if (!fq->flows)
|
||||
return -ENOMEM;
|
||||
|
||||
for (i = 0; i < fq->flows_cnt; i++)
|
||||
fq_flow_init(&fq->flows[i]);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void fq_reset(struct fq *fq,
|
||||
fq_skb_free_t free_func)
|
||||
{
|
||||
int i;
|
||||
|
||||
for (i = 0; i < fq->flows_cnt; i++)
|
||||
fq_flow_reset(fq, &fq->flows[i], free_func);
|
||||
|
||||
kfree(fq->flows);
|
||||
fq->flows = NULL;
|
||||
}
|
||||
|
||||
#endif
|
||||
Загрузка…
Ссылка в новой задаче