From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from nbd.name ([2a01:4f8:221:3d45::2]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jzOQb-0001IR-Dg for ath10k@lists.infradead.org; Sat, 25 Jul 2020 17:57:46 +0000 From: Felix Fietkau Subject: Re: [RFC 0/7] Add support to process rx packets in thread References: <1595351666-28193-1-git-send-email-pillair@codeaurora.org> <20200721172514.GT1339445@lunn.ch> <20200725081633.7432-1-hdanton@sina.com> Message-ID: Date: Sat, 25 Jul 2020 19:57:23 +0200 MIME-Version: 1.0 In-Reply-To: <20200725081633.7432-1-hdanton@sina.com> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "ath10k" Errors-To: ath10k-bounces+kvalo=adurom.com@lists.infradead.org To: Hillf Danton , David Laight , Andrew Lunn , Rakesh Pillai Cc: "netdev@vger.kernel.org" , "linux-wireless@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "ath10k@lists.infradead.org" , "dianders@chromium.org" , Markus Elfring , "evgreen@chromium.org" , "kuba@kernel.org" , "johannes@sipsolutions.net" , "davem@davemloft.net" , "kvalo@codeaurora.org" On 2020-07-25 10:16, Hillf Danton wrote: > Hi folks > > Below is a minimunm poc implementation I can imagine on top of workqueue > to make napi threaded. Thoughts are appreciated. Hi Hillf, For some reason I don't see your mails on linux-wireless/netdev. I've cleaned up your implementation a bit and I ran some tests with mt76 on an mt7621 embedded board. The results look pretty nice, performance is a lot more consistent in my tests now. Here are the changes that I've made compared to your version: - remove the #ifdef, I think it's unnecessary - add a state bit for threaded NAPI - make netif_threaded_napi_add inline - run queue_work outside of local_irq_save/restore (it does that internally already) If you don't mind, I'd like to propose this to netdev soon. Can I have your Signed-off-by for that? Thanks, - Felix --- --- 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_HASHED, /* In NAPI hash (busy polling possible) */ 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_HASHED = BIT(NAPI_STATE_HASHED), 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 { @@ -2315,6 +2318,26 @@ static inline void *netdev_priv(const struct net_device *dev) void netif_napi_add(struct net_device *dev, struct napi_struct *napi, 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 that + */ +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 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -158,6 +158,7 @@ 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; static int netif_rx_internal(struct sk_buff *skb); static int call_netdevice_notifiers_info(unsigned long val, @@ -6286,6 +6287,11 @@ void __napi_schedule(struct napi_struct *n) { 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); @@ -6333,6 +6339,11 @@ 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); @@ -6601,6 +6612,29 @@ static void init_gro_hash(struct napi_struct *napi) napi->gro_bitmask = 0; } +static void napi_workfn(struct work_struct *work) +{ + struct napi_struct *n = container_of(work, struct napi_struct, work); + + for (;;) { + if (!test_bit(NAPI_STATE_SCHED, &n->state)) + return; + + if (n->poll(n, n->weight) < n->weight) + return; + + if (need_resched()) { + /* + * have to pay for the latency of task switch even if + * napi is scheduled + */ + if (test_bit(NAPI_STATE_SCHED, &n->state)) + 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) { @@ -6621,6 +6655,7 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi, #ifdef CONFIG_NETPOLL napi->poll_owner = -1; #endif + INIT_WORK(&napi->work, napi_workfn); set_bit(NAPI_STATE_SCHED, &napi->state); napi_hash_add(napi); } @@ -10676,6 +10711,10 @@ 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); + BUG_ON(!napi_workq); + dev_boot_phase = 0; /* The loopback device is special if any other network devices _______________________________________________ ath10k mailing list ath10k@lists.infradead.org http://lists.infradead.org/mailman/listinfo/ath10k