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Message-Id: <20210506172021.7327-2-yannick.vignon@oss.nxp.com>
Date: Thu, 6 May 2021 19:20:20 +0200
From: Yannick Vignon <yannick.vignon@....nxp.com>
To: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Antoine Tenart <atenart@...nel.org>,
Wei Wang <weiwan@...gle.com>, Taehee Yoo <ap420073@...il.com>,
Alexander Lobakin <alobakin@...me>, netdev@...r.kernel.org,
Giuseppe Cavallaro <peppe.cavallaro@...com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
Jose Abreu <joabreu@...opsys.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Joakim Zhang <qiangqing.zhang@....com>,
sebastien.laveze@....nxp.com
Cc: Yannick Vignon <yannick.vignon@....com>
Subject: [RFC PATCH net-next v1 1/2] net: add name field to napi struct
From: Yannick Vignon <yannick.vignon@....com>
An interesting possibility offered by the new thread NAPI code is to
fine-tune the affinities and priorities of different NAPI instances. In a
real-time networking context, this makes it possible to ensure packets
received in a high-priority queue are always processed, and with low
latency.
However, the way the NAPI threads are named does not really expose which
one is responsible for a given queue. Assigning a more explicit name to
NAPI instances can make that determination much easier.
Signed-off-by: Yannick Vignon <yannick.vignon@....com>
---
include/linux/netdevice.h | 42 +++++++++++++++++++++++++++++++++++++--
net/core/dev.c | 20 +++++++++++++++----
2 files changed, 56 insertions(+), 6 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5cbc950b34df..01fa9d342383 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -318,6 +318,8 @@ struct gro_list {
*/
#define GRO_HASH_BUCKETS 8
+
+#define NAPINAMSIZ 8
/*
* Structure for NAPI scheduling similar to tasklet but with weighting
*/
@@ -348,6 +350,7 @@ struct napi_struct {
struct hlist_node napi_hash_node;
unsigned int napi_id;
struct task_struct *thread;
+ char name[NAPINAMSIZ];
};
enum {
@@ -2445,6 +2448,21 @@ static inline void *netdev_priv(const struct net_device *dev)
*/
#define NAPI_POLL_WEIGHT 64
+/**
+ * netif_napi_add_named - initialize a NAPI context
+ * @dev: network device
+ * @napi: NAPI context
+ * @poll: polling function
+ * @weight: default weight
+ * @name: napi instance name
+ *
+ * netif_napi_add_named() must be used to initialize a NAPI context prior to calling
+ * *any* of the other NAPI-related functions.
+ */
+void netif_napi_add_named(struct net_device *dev, struct napi_struct *napi,
+ int (*poll)(struct napi_struct *, int), int weight,
+ const char *name);
+
/**
* netif_napi_add - initialize a NAPI context
* @dev: network device
@@ -2458,6 +2476,27 @@ 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_tx_napi_add_named - initialize a NAPI context
+ * @dev: network device
+ * @napi: NAPI context
+ * @poll: polling function
+ * @weight: default weight
+ * @name: napi instance name
+ *
+ * This variant of netif_napi_add_named() should be used from drivers using NAPI
+ * to exclusively poll a TX queue.
+ * This will avoid we add it into napi_hash[], thus polluting this hash table.
+ */
+static inline void netif_tx_napi_add_named(struct net_device *dev,
+ struct napi_struct *napi,
+ int (*poll)(struct napi_struct *, int),
+ int weight, const char *name)
+{
+ set_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state);
+ netif_napi_add_named(dev, napi, poll, weight, name);
+}
+
/**
* netif_tx_napi_add - initialize a NAPI context
* @dev: network device
@@ -2474,8 +2513,7 @@ static inline void netif_tx_napi_add(struct net_device *dev,
int (*poll)(struct napi_struct *, int),
int weight)
{
- set_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state);
- netif_napi_add(dev, napi, poll, weight);
+ netif_tx_napi_add_named(dev, napi, poll, weight, NULL);
}
/**
diff --git a/net/core/dev.c b/net/core/dev.c
index 222b1d322c96..bc70f545cc5a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1563,8 +1563,8 @@ static int napi_kthread_create(struct napi_struct *n)
* TASK_INTERRUPTIBLE mode to avoid the blocked task
* warning and work with loadavg.
*/
- n->thread = kthread_run(napi_threaded_poll, n, "napi/%s-%d",
- n->dev->name, n->napi_id);
+ n->thread = kthread_run(napi_threaded_poll, n, "napi/%s-%s",
+ n->dev->name, n->name);
if (IS_ERR(n->thread)) {
err = PTR_ERR(n->thread);
pr_err("kthread_run failed with err %d\n", err);
@@ -6844,8 +6844,9 @@ int dev_set_threaded(struct net_device *dev, bool threaded)
}
EXPORT_SYMBOL(dev_set_threaded);
-void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
- int (*poll)(struct napi_struct *, int), int weight)
+void netif_napi_add_named(struct net_device *dev, struct napi_struct *napi,
+ int (*poll)(struct napi_struct *, int), int weight,
+ const char *name)
{
if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
return;
@@ -6871,6 +6872,10 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
set_bit(NAPI_STATE_NPSVC, &napi->state);
list_add_rcu(&napi->dev_list, &dev->napi_list);
napi_hash_add(napi);
+ if (name)
+ strncpy(napi->name, name, NAPINAMSIZ);
+ else
+ snprintf(napi->name, NAPINAMSIZ, "%d", napi->napi_id);
/* Create kthread for this napi if dev->threaded is set.
* Clear dev->threaded if kthread creation failed so that
* threaded mode will not be enabled in napi_enable().
@@ -6878,6 +6883,13 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
if (dev->threaded && napi_kthread_create(napi))
dev->threaded = 0;
}
+EXPORT_SYMBOL(netif_napi_add_named);
+
+void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
+ int (*poll)(struct napi_struct *, int), int weight)
+{
+ netif_napi_add_named(dev, napi, poll, weight, NULL);
+}
EXPORT_SYMBOL(netif_napi_add);
void napi_disable(struct napi_struct *n)
--
2.17.1
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