From: Felix Fietkau <nbd@nbd.name>
To: Hillf Danton <hdanton@sina.com>,
David Laight <David.Laight@ACULAB.COM>,
Andrew Lunn <andrew@lunn.ch>,
Rakesh Pillai <pillair@codeaurora.org>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>,
"dianders@chromium.org" <dianders@chromium.org>,
Markus Elfring <Markus.Elfring@web.de>,
"evgreen@chromium.org" <evgreen@chromium.org>,
"kuba@kernel.org" <kuba@kernel.org>,
"johannes@sipsolutions.net" <johannes@sipsolutions.net>,
"davem@davemloft.net" <davem@davemloft.net>,
"kvalo@codeaurora.org" <kvalo@codeaurora.org>
Subject: Re: [RFC 0/7] Add support to process rx packets in thread
Date: Sat, 25 Jul 2020 19:57:23 +0200 [thread overview]
Message-ID: <a50ebfba-9733-48db-c90b-5fc106e67f29@nbd.name> (raw)
In-Reply-To: <20200725081633.7432-1-hdanton@sina.com>
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
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next prev parent reply other threads:[~2020-07-25 17:57 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 17:14 [RFC 0/7] Add support to process rx packets in thread Rakesh Pillai
2020-07-21 17:14 ` [RFC 1/7] mac80211: Add check for napi handle before WARN_ON Rakesh Pillai
2020-07-22 12:56 ` Johannes Berg
2020-07-23 18:26 ` Rakesh Pillai
2020-07-23 20:06 ` Johannes Berg
2020-07-24 6:21 ` Rakesh Pillai
2020-07-26 16:19 ` Rakesh Pillai
2020-07-30 12:40 ` Johannes Berg
2020-07-21 17:14 ` [RFC 2/7] ath10k: Add support to process rx packet in thread Rakesh Pillai
2020-07-21 21:53 ` Rajkumar Manoharan
2020-07-22 12:27 ` Felix Fietkau
2020-07-22 12:55 ` Johannes Berg
2020-07-22 13:00 ` Felix Fietkau
2020-07-23 6:09 ` Rajkumar Manoharan
2021-03-22 23:57 ` Ben Greear
2021-03-23 1:20 ` Brian Norris
2021-03-23 3:01 ` Ben Greear
2021-03-23 7:45 ` Felix Fietkau
2021-03-25 9:45 ` Rakesh Pillai
2021-03-25 10:33 ` Felix Fietkau
2020-07-23 18:25 ` Rakesh Pillai
2020-07-24 23:11 ` Jacob Keller
2020-07-21 17:14 ` [RFC 3/7] ath10k: Add module param to enable rx thread Rakesh Pillai
2020-07-21 17:14 ` [RFC 4/7] ath10k: Do not exhaust budget on process tx completion Rakesh Pillai
2020-07-21 17:14 ` [RFC 5/7] ath10k: Handle the rx packet processing in thread Rakesh Pillai
2020-07-21 17:14 ` [RFC 6/7] ath10k: Add deliver to stack from thread context Rakesh Pillai
2020-07-21 17:14 ` [RFC 7/7] ath10k: Handle rx thread suspend and resume Rakesh Pillai
2020-07-23 23:06 ` Sebastian Gottschall
2020-07-24 6:19 ` Rakesh Pillai
2020-07-21 17:25 ` [RFC 0/7] Add support to process rx packets in thread Andrew Lunn
2020-07-21 18:05 ` Florian Fainelli
2020-07-23 18:21 ` Rakesh Pillai
2020-07-23 19:02 ` Florian Fainelli
2020-07-24 6:20 ` Rakesh Pillai
2020-07-24 22:28 ` Florian Fainelli
2020-07-22 9:12 ` David Laight
2020-07-25 8:16 ` Hillf Danton
2020-07-25 10:38 ` Sebastian Gottschall
2020-07-25 12:25 ` Hillf Danton
2020-07-25 14:08 ` Sebastian Gottschall
2020-07-25 14:57 ` Hillf Danton
2020-07-25 15:41 ` Sebastian Gottschall
2020-07-26 11:16 ` David Laight
2020-07-28 16:59 ` Rakesh Pillai
2020-07-29 1:34 ` Hillf Danton
2020-07-25 17:57 ` Felix Fietkau [this message]
2020-07-26 1:22 ` Hillf Danton
2020-07-26 8:10 ` Felix Fietkau
2020-07-26 8:32 ` Hillf Danton
2020-07-26 8:59 ` Felix Fietkau
2020-07-22 16:20 ` Jakub Kicinski
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