diff options
Diffstat (limited to 'target/linux/generic/pending-5.10/690-net-add-support-for-threaded-NAPI-polling.patch')
-rw-r--r-- | target/linux/generic/pending-5.10/690-net-add-support-for-threaded-NAPI-polling.patch | 301 |
1 files changed, 0 insertions, 301 deletions
diff --git a/target/linux/generic/pending-5.10/690-net-add-support-for-threaded-NAPI-polling.patch b/target/linux/generic/pending-5.10/690-net-add-support-for-threaded-NAPI-polling.patch deleted file mode 100644 index 9b1bd6e976..0000000000 --- a/target/linux/generic/pending-5.10/690-net-add-support-for-threaded-NAPI-polling.patch +++ /dev/null @@ -1,301 +0,0 @@ -From: Felix Fietkau <nbd@nbd.name> -Date: Sun, 26 Jul 2020 14:03:21 +0200 -Subject: [PATCH] net: add support for threaded NAPI polling - -For some drivers (especially 802.11 drivers), doing a lot of work in the NAPI -poll function does not perform well. Since NAPI poll is bound to the CPU it -was scheduled from, we can easily end up with a few very busy CPUs spending -most of their time in softirq/ksoftirqd and some idle ones. - -Introduce threaded NAPI for such drivers based on a workqueue. The API is the -same except for using netif_threaded_napi_add instead of netif_napi_add. - -In my tests with mt76 on MT7621 using threaded NAPI + a thread for tx scheduling -improves LAN->WLAN bridging throughput by 10-50%. Throughput without threaded -NAPI is wildly inconsistent, depending on the CPU that runs the tx scheduling -thread. - -With threaded NAPI, throughput seems stable and consistent (and higher than -the best results I got without it). - -Based on a patch by Hillf Danton - -Cc: Hillf Danton <hdanton@sina.com> -Signed-off-by: Felix Fietkau <nbd@nbd.name> ---- - ---- a/include/linux/netdevice.h -+++ b/include/linux/netdevice.h -@@ -347,6 +347,7 @@ struct napi_struct { - struct list_head dev_list; - struct hlist_node napi_hash_node; - unsigned int napi_id; -+ struct work_struct work; - }; - - enum { -@@ -357,6 +358,7 @@ enum { - NAPI_STATE_LISTED, /* NAPI added to system lists */ - NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */ - NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */ -+ NAPI_STATE_THREADED, /* Use threaded NAPI */ - }; - - enum { -@@ -367,6 +369,7 @@ enum { - NAPIF_STATE_LISTED = BIT(NAPI_STATE_LISTED), - NAPIF_STATE_NO_BUSY_POLL = BIT(NAPI_STATE_NO_BUSY_POLL), - NAPIF_STATE_IN_BUSY_POLL = BIT(NAPI_STATE_IN_BUSY_POLL), -+ NAPIF_STATE_THREADED = BIT(NAPI_STATE_THREADED), - }; - - enum gro_result { -@@ -2211,6 +2214,7 @@ struct net_device { - struct lock_class_key *qdisc_running_key; - bool proto_down; - unsigned wol_enabled:1; -+ unsigned threaded:1; - - struct list_head net_notifier_list; - -@@ -2413,6 +2417,26 @@ void netif_napi_add(struct net_device *d - int (*poll)(struct napi_struct *, int), int weight); - - /** -+ * netif_threaded_napi_add - initialize a NAPI context -+ * @dev: network device -+ * @napi: NAPI context -+ * @poll: polling function -+ * @weight: default weight -+ * -+ * This variant of netif_napi_add() should be used from drivers using NAPI -+ * with CPU intensive poll functions. -+ * This will schedule polling from a high priority workqueue -+ */ -+static inline void netif_threaded_napi_add(struct net_device *dev, -+ struct napi_struct *napi, -+ int (*poll)(struct napi_struct *, int), -+ int weight) -+{ -+ set_bit(NAPI_STATE_THREADED, &napi->state); -+ netif_napi_add(dev, napi, poll, weight); -+} -+ -+/** - * netif_tx_napi_add - initialize a NAPI context - * @dev: network device - * @napi: NAPI context ---- a/net/core/dev.c -+++ b/net/core/dev.c -@@ -159,6 +159,7 @@ static DEFINE_SPINLOCK(offload_lock); - struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly; - struct list_head ptype_all __read_mostly; /* Taps */ - static struct list_head offload_base __read_mostly; -+static struct workqueue_struct *napi_workq __read_mostly; - - static int netif_rx_internal(struct sk_buff *skb); - static int call_netdevice_notifiers_info(unsigned long val, -@@ -6407,6 +6408,11 @@ void __napi_schedule(struct napi_struct - { - unsigned long flags; - -+ if (test_bit(NAPI_STATE_THREADED, &n->state)) { -+ queue_work(napi_workq, &n->work); -+ return; -+ } -+ - local_irq_save(flags); - ____napi_schedule(this_cpu_ptr(&softnet_data), n); - local_irq_restore(flags); -@@ -6454,6 +6460,11 @@ EXPORT_SYMBOL(napi_schedule_prep); - */ - void __napi_schedule_irqoff(struct napi_struct *n) - { -+ if (test_bit(NAPI_STATE_THREADED, &n->state)) { -+ queue_work(napi_workq, &n->work); -+ return; -+ } -+ - ____napi_schedule(this_cpu_ptr(&softnet_data), n); - } - EXPORT_SYMBOL(__napi_schedule_irqoff); -@@ -6715,12 +6726,94 @@ static void init_gro_hash(struct napi_st - napi->gro_bitmask = 0; - } - -+static int __napi_poll(struct napi_struct *n, bool *repoll) -+{ -+ int work, weight; -+ -+ weight = n->weight; -+ -+ /* This NAPI_STATE_SCHED test is for avoiding a race -+ * with netpoll's poll_napi(). Only the entity which -+ * obtains the lock and sees NAPI_STATE_SCHED set will -+ * actually make the ->poll() call. Therefore we avoid -+ * accidentally calling ->poll() when NAPI is not scheduled. -+ */ -+ work = 0; -+ if (test_bit(NAPI_STATE_SCHED, &n->state)) { -+ work = n->poll(n, weight); -+ trace_napi_poll(n, work, weight); -+ } -+ -+ if (unlikely(work > weight)) -+ pr_err_once("NAPI poll function %pS returned %d, exceeding its budget of %d.\n", -+ n->poll, work, weight); -+ -+ if (likely(work < weight)) -+ return work; -+ -+ /* Drivers must not modify the NAPI state if they -+ * consume the entire weight. In such cases this code -+ * still "owns" the NAPI instance and therefore can -+ * move the instance around on the list at-will. -+ */ -+ if (unlikely(napi_disable_pending(n))) { -+ napi_complete(n); -+ return work; -+ } -+ -+ if (n->gro_bitmask) { -+ /* flush too old packets -+ * If HZ < 1000, flush all packets. -+ */ -+ napi_gro_flush(n, HZ >= 1000); -+ } -+ -+ gro_normal_list(n); -+ -+ *repoll = true; -+ -+ return work; -+} -+ -+static void napi_workfn(struct work_struct *work) -+{ -+ struct napi_struct *n = container_of(work, struct napi_struct, work); -+ void *have; -+ -+ for (;;) { -+ bool repoll = false; -+ -+ local_bh_disable(); -+ -+ have = netpoll_poll_lock(n); -+ __napi_poll(n, &repoll); -+ netpoll_poll_unlock(have); -+ -+ local_bh_enable(); -+ -+ if (!repoll) -+ return; -+ -+ if (!need_resched()) -+ continue; -+ -+ /* -+ * have to pay for the latency of task switch even if -+ * napi is scheduled -+ */ -+ queue_work(napi_workq, work); -+ return; -+ } -+} -+ - void netif_napi_add(struct net_device *dev, struct napi_struct *napi, - int (*poll)(struct napi_struct *, int), int weight) - { - if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state))) - return; - -+ if (dev->threaded) -+ set_bit(NAPI_STATE_THREADED, &napi->state); - INIT_LIST_HEAD(&napi->poll_list); - INIT_HLIST_NODE(&napi->napi_hash_node); - hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED); -@@ -6738,6 +6831,7 @@ void netif_napi_add(struct net_device *d - #ifdef CONFIG_NETPOLL - napi->poll_owner = -1; - #endif -+ INIT_WORK(&napi->work, napi_workfn); - set_bit(NAPI_STATE_SCHED, &napi->state); - set_bit(NAPI_STATE_NPSVC, &napi->state); - list_add_rcu(&napi->dev_list, &dev->napi_list); -@@ -6780,6 +6874,7 @@ void __netif_napi_del(struct napi_struct - if (!test_and_clear_bit(NAPI_STATE_LISTED, &napi->state)) - return; - -+ cancel_work_sync(&napi->work); - napi_hash_del(napi); - list_del_rcu(&napi->dev_list); - napi_free_frags(napi); -@@ -6791,53 +6886,19 @@ EXPORT_SYMBOL(__netif_napi_del); - - static int napi_poll(struct napi_struct *n, struct list_head *repoll) - { -+ bool do_repoll = false; - void *have; -- int work, weight; -+ int work; - - list_del_init(&n->poll_list); - - have = netpoll_poll_lock(n); - -- weight = n->weight; -+ work = __napi_poll(n, &do_repoll); - -- /* This NAPI_STATE_SCHED test is for avoiding a race -- * with netpoll's poll_napi(). Only the entity which -- * obtains the lock and sees NAPI_STATE_SCHED set will -- * actually make the ->poll() call. Therefore we avoid -- * accidentally calling ->poll() when NAPI is not scheduled. -- */ -- work = 0; -- if (test_bit(NAPI_STATE_SCHED, &n->state)) { -- work = n->poll(n, weight); -- trace_napi_poll(n, work, weight); -- } -- -- if (unlikely(work > weight)) -- pr_err_once("NAPI poll function %pS returned %d, exceeding its budget of %d.\n", -- n->poll, work, weight); -- -- if (likely(work < weight)) -+ if (!do_repoll) - goto out_unlock; - -- /* Drivers must not modify the NAPI state if they -- * consume the entire weight. In such cases this code -- * still "owns" the NAPI instance and therefore can -- * move the instance around on the list at-will. -- */ -- if (unlikely(napi_disable_pending(n))) { -- napi_complete(n); -- goto out_unlock; -- } -- -- if (n->gro_bitmask) { -- /* flush too old packets -- * If HZ < 1000, flush all packets. -- */ -- napi_gro_flush(n, HZ >= 1000); -- } -- -- gro_normal_list(n); -- - /* Some drivers may have called napi_schedule - * prior to exhausting their budget. - */ -@@ -11333,6 +11394,10 @@ static int __init net_dev_init(void) - sd->backlog.weight = weight_p; - } - -+ napi_workq = alloc_workqueue("napi_workq", WQ_UNBOUND | WQ_HIGHPRI, -+ WQ_UNBOUND_MAX_ACTIVE | WQ_SYSFS); -+ BUG_ON(!napi_workq); -+ - dev_boot_phase = 0; - - /* The loopback device is special if any other network devices |