318 lines
8.2 KiB
Diff
318 lines
8.2 KiB
Diff
From: Felix Fietkau <nbd@nbd.name>
|
|
Date: Wed, 25 Nov 2020 18:10:34 +0100
|
|
Subject: [PATCH] net/fq_impl: do not maintain a backlog-sorted list of
|
|
flows
|
|
|
|
A sorted flow list is only needed to drop packets in the biggest flow when
|
|
hitting the overmemory condition.
|
|
By scanning flows only when needed, we can avoid paying the cost of
|
|
maintaining the list under normal conditions
|
|
In order to avoid scanning lots of empty flows and touching too many cold
|
|
cache lines, a bitmap of flows with backlog is maintained
|
|
|
|
Signed-off-by: Felix Fietkau <nbd@nbd.name>
|
|
---
|
|
|
|
--- a/include/net/fq.h
|
|
+++ b/include/net/fq.h
|
|
@@ -19,8 +19,6 @@ struct fq_tin;
|
|
* @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
|
|
@@ -29,7 +27,6 @@ struct fq_tin;
|
|
struct fq_flow {
|
|
struct fq_tin *tin;
|
|
struct list_head flowchain;
|
|
- struct list_head backlogchain;
|
|
struct sk_buff_head queue;
|
|
u32 backlog;
|
|
int deficit;
|
|
@@ -47,6 +44,7 @@ struct fq_flow {
|
|
struct fq_tin {
|
|
struct list_head new_flows;
|
|
struct list_head old_flows;
|
|
+ struct list_head tin_list;
|
|
struct fq_flow default_flow;
|
|
u32 backlog_bytes;
|
|
u32 backlog_packets;
|
|
@@ -60,14 +58,14 @@ struct fq_tin {
|
|
/**
|
|
* 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;
|
|
+ unsigned long *flows_bitmap;
|
|
+
|
|
+ struct list_head tin_backlog;
|
|
spinlock_t lock;
|
|
u32 flows_cnt;
|
|
u32 limit;
|
|
--- a/include/net/fq_impl.h
|
|
+++ b/include/net/fq_impl.h
|
|
@@ -17,12 +17,24 @@ __fq_adjust_removal(struct fq *fq, struc
|
|
unsigned int bytes, unsigned int truesize)
|
|
{
|
|
struct fq_tin *tin = flow->tin;
|
|
+ int idx;
|
|
|
|
tin->backlog_bytes -= bytes;
|
|
tin->backlog_packets -= packets;
|
|
flow->backlog -= bytes;
|
|
fq->backlog -= packets;
|
|
fq->memory_usage -= truesize;
|
|
+
|
|
+ if (flow->backlog)
|
|
+ return;
|
|
+
|
|
+ if (flow == &tin->default_flow) {
|
|
+ list_del_init(&tin->tin_list);
|
|
+ return;
|
|
+ }
|
|
+
|
|
+ idx = flow - fq->flows;
|
|
+ __clear_bit(idx, fq->flows_bitmap);
|
|
}
|
|
|
|
static void fq_adjust_removal(struct fq *fq,
|
|
@@ -32,24 +44,6 @@ static void fq_adjust_removal(struct fq
|
|
__fq_adjust_removal(fq, flow, 1, skb->len, skb->truesize);
|
|
}
|
|
|
|
-static void fq_rejigger_backlog(struct fq *fq, struct fq_flow *flow)
|
|
-{
|
|
- struct fq_flow *i;
|
|
-
|
|
- 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);
|
|
- }
|
|
-}
|
|
-
|
|
static struct sk_buff *fq_flow_dequeue(struct fq *fq,
|
|
struct fq_flow *flow)
|
|
{
|
|
@@ -62,7 +56,6 @@ static struct sk_buff *fq_flow_dequeue(s
|
|
return NULL;
|
|
|
|
fq_adjust_removal(fq, flow, skb);
|
|
- fq_rejigger_backlog(fq, flow);
|
|
|
|
return skb;
|
|
}
|
|
@@ -90,7 +83,6 @@ static int fq_flow_drop(struct fq *fq, s
|
|
} while (packets < pending);
|
|
|
|
__fq_adjust_removal(fq, flow, packets, bytes, truesize);
|
|
- fq_rejigger_backlog(fq, flow);
|
|
|
|
return packets;
|
|
}
|
|
@@ -170,22 +162,36 @@ static struct fq_flow *fq_flow_classify(
|
|
return flow;
|
|
}
|
|
|
|
-static void fq_recalc_backlog(struct fq *fq,
|
|
- struct fq_tin *tin,
|
|
- struct fq_flow *flow)
|
|
-{
|
|
- struct fq_flow *i;
|
|
-
|
|
- 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;
|
|
+static struct fq_flow *fq_find_fattest_flow(struct fq *fq)
|
|
+{
|
|
+ struct fq_tin *tin;
|
|
+ struct fq_flow *flow = NULL;
|
|
+ u32 len = 0;
|
|
+ int i;
|
|
+
|
|
+ for_each_set_bit(i, fq->flows_bitmap, fq->flows_cnt) {
|
|
+ struct fq_flow *cur = &fq->flows[i];
|
|
+ unsigned int cur_len;
|
|
+
|
|
+ cur_len = cur->backlog;
|
|
+ if (cur_len <= len)
|
|
+ continue;
|
|
+
|
|
+ flow = cur;
|
|
+ len = cur_len;
|
|
+ }
|
|
|
|
- list_move(&flow->backlogchain, &i->backlogchain);
|
|
+ list_for_each_entry(tin, &fq->tin_backlog, tin_list) {
|
|
+ unsigned int cur_len = tin->default_flow.backlog;
|
|
+
|
|
+ if (cur_len <= len)
|
|
+ continue;
|
|
+
|
|
+ flow = &tin->default_flow;
|
|
+ len = cur_len;
|
|
+ }
|
|
+
|
|
+ return flow;
|
|
}
|
|
|
|
static void fq_tin_enqueue(struct fq *fq,
|
|
@@ -200,6 +206,13 @@ static void fq_tin_enqueue(struct fq *fq
|
|
|
|
flow = fq_flow_classify(fq, tin, idx, skb);
|
|
|
|
+ if (!flow->backlog) {
|
|
+ if (flow != &tin->default_flow)
|
|
+ __set_bit(idx, fq->flows_bitmap);
|
|
+ else if (list_empty(&tin->tin_list))
|
|
+ list_add(&tin->tin_list, &fq->tin_backlog);
|
|
+ }
|
|
+
|
|
flow->tin = tin;
|
|
flow->backlog += skb->len;
|
|
tin->backlog_bytes += skb->len;
|
|
@@ -207,8 +220,6 @@ static void fq_tin_enqueue(struct fq *fq
|
|
fq->memory_usage += skb->truesize;
|
|
fq->backlog++;
|
|
|
|
- fq_recalc_backlog(fq, tin, flow);
|
|
-
|
|
if (list_empty(&flow->flowchain)) {
|
|
flow->deficit = fq->quantum;
|
|
list_add_tail(&flow->flowchain,
|
|
@@ -218,9 +229,7 @@ static void fq_tin_enqueue(struct fq *fq
|
|
__skb_queue_tail(&flow->queue, skb);
|
|
oom = (fq->memory_usage > fq->memory_limit);
|
|
while (fq->backlog > fq->limit || oom) {
|
|
- flow = list_first_entry_or_null(&fq->backlogs,
|
|
- struct fq_flow,
|
|
- backlogchain);
|
|
+ flow = fq_find_fattest_flow(fq);
|
|
if (!flow)
|
|
return;
|
|
|
|
@@ -255,8 +264,6 @@ static void fq_flow_filter(struct fq *fq
|
|
fq_adjust_removal(fq, flow, skb);
|
|
free_func(fq, tin, flow, skb);
|
|
}
|
|
-
|
|
- fq_rejigger_backlog(fq, flow);
|
|
}
|
|
|
|
static void fq_tin_filter(struct fq *fq,
|
|
@@ -279,16 +286,18 @@ static void fq_flow_reset(struct fq *fq,
|
|
struct fq_flow *flow,
|
|
fq_skb_free_t free_func)
|
|
{
|
|
+ struct fq_tin *tin = flow->tin;
|
|
struct sk_buff *skb;
|
|
|
|
while ((skb = fq_flow_dequeue(fq, flow)))
|
|
- free_func(fq, flow->tin, flow, skb);
|
|
+ free_func(fq, tin, flow, skb);
|
|
|
|
- if (!list_empty(&flow->flowchain))
|
|
+ if (!list_empty(&flow->flowchain)) {
|
|
list_del_init(&flow->flowchain);
|
|
-
|
|
- if (!list_empty(&flow->backlogchain))
|
|
- list_del_init(&flow->backlogchain);
|
|
+ if (list_empty(&tin->new_flows) &&
|
|
+ list_empty(&tin->old_flows))
|
|
+ list_del_init(&tin->tin_list);
|
|
+ }
|
|
|
|
flow->tin = NULL;
|
|
|
|
@@ -314,6 +323,7 @@ static void fq_tin_reset(struct fq *fq,
|
|
fq_flow_reset(fq, flow, free_func);
|
|
}
|
|
|
|
+ WARN_ON_ONCE(!list_empty(&tin->tin_list));
|
|
WARN_ON_ONCE(tin->backlog_bytes);
|
|
WARN_ON_ONCE(tin->backlog_packets);
|
|
}
|
|
@@ -321,7 +331,6 @@ static void fq_tin_reset(struct fq *fq,
|
|
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);
|
|
}
|
|
|
|
@@ -329,6 +338,7 @@ static void fq_tin_init(struct fq_tin *t
|
|
{
|
|
INIT_LIST_HEAD(&tin->new_flows);
|
|
INIT_LIST_HEAD(&tin->old_flows);
|
|
+ INIT_LIST_HEAD(&tin->tin_list);
|
|
fq_flow_init(&tin->default_flow);
|
|
}
|
|
|
|
@@ -337,8 +347,8 @@ static int fq_init(struct fq *fq, int fl
|
|
int i;
|
|
|
|
memset(fq, 0, sizeof(fq[0]));
|
|
- INIT_LIST_HEAD(&fq->backlogs);
|
|
spin_lock_init(&fq->lock);
|
|
+ INIT_LIST_HEAD(&fq->tin_backlog);
|
|
fq->flows_cnt = max_t(u32, flows_cnt, 1);
|
|
fq->quantum = 300;
|
|
fq->limit = 8192;
|
|
@@ -348,6 +358,14 @@ static int fq_init(struct fq *fq, int fl
|
|
if (!fq->flows)
|
|
return -ENOMEM;
|
|
|
|
+ fq->flows_bitmap = kcalloc(BITS_TO_LONGS(fq->flows_cnt), sizeof(long),
|
|
+ GFP_KERNEL);
|
|
+ if (!fq->flows_bitmap) {
|
|
+ kvfree(fq->flows);
|
|
+ fq->flows = NULL;
|
|
+ return -ENOMEM;
|
|
+ }
|
|
+
|
|
for (i = 0; i < fq->flows_cnt; i++)
|
|
fq_flow_init(&fq->flows[i]);
|
|
|
|
@@ -364,6 +382,9 @@ static void fq_reset(struct fq *fq,
|
|
|
|
kvfree(fq->flows);
|
|
fq->flows = NULL;
|
|
+
|
|
+ kfree(fq->flows_bitmap);
|
|
+ fq->flows_bitmap = NULL;
|
|
}
|
|
|
|
#endif
|
|
--- a/net/mac80211/tx.c
|
|
+++ b/net/mac80211/tx.c
|
|
@@ -3335,8 +3335,6 @@ out_recalc:
|
|
if (head->len != orig_len) {
|
|
flow->backlog += head->len - orig_len;
|
|
tin->backlog_bytes += head->len - orig_len;
|
|
-
|
|
- fq_recalc_backlog(fq, tin, flow);
|
|
}
|
|
out:
|
|
spin_unlock_bh(&fq->lock);
|