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Message-ID: <20250204220622.156061-3-ahmed.zaki@intel.com>
Date: Tue,  4 Feb 2025 15:06:19 -0700
From: Ahmed Zaki <ahmed.zaki@...el.com>
To: netdev@...r.kernel.org
Cc: intel-wired-lan@...ts.osuosl.org,
	andrew+netdev@...n.ch,
	edumazet@...gle.com,
	kuba@...nel.org,
	horms@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	michael.chan@...adcom.com,
	tariqt@...dia.com,
	anthony.l.nguyen@...el.com,
	przemyslaw.kitszel@...el.com,
	jdamato@...tly.com,
	shayd@...dia.com,
	akpm@...ux-foundation.org,
	shayagr@...zon.com,
	kalesh-anakkur.purayil@...adcom.com,
	Ahmed Zaki <ahmed.zaki@...el.com>
Subject: [PATCH net-next v7 2/5] net: napi: add CPU affinity to napi_config

A common task for most drivers is to remember the user-set CPU affinity
to its IRQs. On each netdev reset, the driver should re-assign the
user's settings to the IRQs.

Add CPU affinity mask to napi_config. To delegate the CPU affinity
management to the core, drivers must:
 1 - set the new netdev flag "irq_affinity_auto":
                                       netif_enable_irq_affinity(netdev)
 2 - create the napi with persistent config:
                                       netif_napi_add_config()
 3 - bind an IRQ to the napi instance: netif_napi_set_irq()

the core will then make sure to use re-assign affinity to the napi's
IRQ.

The default IRQ mask is set to one cpu starting from the closest NUMA.

Signed-off-by: Ahmed Zaki <ahmed.zaki@...el.com>
---
 include/linux/netdevice.h | 14 +++++++--
 net/core/dev.c            | 62 +++++++++++++++++++++++++++++++--------
 2 files changed, 61 insertions(+), 15 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0d19fa98b65e..0436605ee607 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -352,6 +352,7 @@ struct napi_config {
 	u64 gro_flush_timeout;
 	u64 irq_suspend_timeout;
 	u32 defer_hard_irqs;
+	cpumask_t affinity_mask;
 	unsigned int napi_id;
 };
 
@@ -394,10 +395,8 @@ struct napi_struct {
 	struct list_head	dev_list;
 	struct hlist_node	napi_hash_node;
 	int			irq;
-#ifdef CONFIG_RFS_ACCEL
 	struct irq_affinity_notify notify;
 	int			napi_rmap_idx;
-#endif
 	int			index;
 	struct napi_config	*config;
 };
@@ -1992,6 +1991,11 @@ enum netdev_reg_state {
  *
  *	@threaded:	napi threaded mode is enabled
  *
+ *	@irq_affinity_auto: driver wants the core to manage the IRQ affinity.
+ *			    Set by netif_enable_irq_affinity(), then driver must
+ *			    create persistent napi by netif_napi_add_config()
+ *			    and finally bind napi to IRQ (netif_napi_set_irq).
+ *
  *	@rx_cpu_rmap_auto: driver wants the core to manage the ARFS rmap.
  *	                   Set by calling netif_enable_cpu_rmap().
  *
@@ -2402,6 +2406,7 @@ struct net_device {
 	struct lock_class_key	*qdisc_tx_busylock;
 	bool			proto_down;
 	bool			threaded;
+	bool			irq_affinity_auto;
 	bool			rx_cpu_rmap_auto;
 
 	/* priv_flags_slow, ungrouped to save space */
@@ -2662,6 +2667,11 @@ static inline void netdev_set_ml_priv(struct net_device *dev,
 	dev->ml_priv_type = type;
 }
 
+static inline void netif_enable_irq_affinity(struct net_device *dev)
+{
+	dev->irq_affinity_auto = true;
+}
+
 /*
  * Net namespace inlines
  */
diff --git a/net/core/dev.c b/net/core/dev.c
index 33e84477c9c2..4cde7ac31e74 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6866,28 +6866,39 @@ void netif_queue_set_napi(struct net_device *dev, unsigned int queue_index,
 }
 EXPORT_SYMBOL(netif_queue_set_napi);
 
-#ifdef CONFIG_RFS_ACCEL
 static void
-netif_irq_cpu_rmap_notify(struct irq_affinity_notify *notify,
-			  const cpumask_t *mask)
+netif_napi_irq_notify(struct irq_affinity_notify *notify,
+		      const cpumask_t *mask)
 {
 	struct napi_struct *napi =
 		container_of(notify, struct napi_struct, notify);
+#ifdef CONFIG_RFS_ACCEL
 	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
 	int err;
+#endif
 
-	err = cpu_rmap_update(rmap, napi->napi_rmap_idx, mask);
-	if (err)
-		netdev_warn(napi->dev, "RMAP update failed (%d)\n",
-			    err);
+	if (napi->config && napi->dev->irq_affinity_auto)
+		cpumask_copy(&napi->config->affinity_mask, mask);
+
+#ifdef CONFIG_RFS_ACCEL
+	if (napi->dev->rx_cpu_rmap_auto) {
+		err = cpu_rmap_update(rmap, napi->napi_rmap_idx, mask);
+		if (err)
+			netdev_warn(napi->dev, "RMAP update failed (%d)\n",
+				    err);
+	}
+#endif
 }
 
+#ifdef CONFIG_RFS_ACCEL
 static void netif_napi_affinity_release(struct kref *ref)
 {
 	struct napi_struct *napi =
 		container_of(ref, struct napi_struct, notify.kref);
 	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
 
+	if (!napi->dev->rx_cpu_rmap_auto)
+		return;
 	rmap->obj[napi->napi_rmap_idx] = NULL;
 	napi->napi_rmap_idx = -1;
 	cpu_rmap_put(rmap);
@@ -6898,7 +6909,7 @@ static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
 	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
 	int rc;
 
-	napi->notify.notify = netif_irq_cpu_rmap_notify;
+	napi->notify.notify = netif_napi_irq_notify;
 	napi->notify.release = netif_napi_affinity_release;
 	cpu_rmap_get(rmap);
 	rc = cpu_rmap_add(rmap, napi);
@@ -6948,6 +6959,10 @@ static void netif_del_cpu_rmap(struct net_device *dev)
 }
 
 #else
+static void netif_napi_affinity_release(struct kref *ref)
+{
+}
+
 static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
 {
 	return 0;
@@ -6968,17 +6983,28 @@ void netif_napi_set_irq_locked(struct napi_struct *napi, int irq)
 {
 	int rc;
 
-	/* Remove existing rmap entries */
-	if (napi->dev->rx_cpu_rmap_auto &&
+	/* Remove existing resources */
+	if ((napi->dev->rx_cpu_rmap_auto || napi->dev->irq_affinity_auto) &&
 	    napi->irq != irq && napi->irq > 0)
 		irq_set_affinity_notifier(napi->irq, NULL);
 
 	napi->irq = irq;
-	if (irq > 0) {
+	if (irq < 0)
+		return;
+
+	if (napi->dev->rx_cpu_rmap_auto) {
 		rc = napi_irq_cpu_rmap_add(napi, irq);
 		if (rc)
 			netdev_warn(napi->dev, "Unable to update ARFS map (%d)\n",
 				    rc);
+	} else if (napi->config && napi->dev->irq_affinity_auto) {
+		napi->notify.notify = netif_napi_irq_notify;
+		napi->notify.release = netif_napi_affinity_release;
+
+		rc = irq_set_affinity_notifier(irq, &napi->notify);
+		if (rc)
+			netdev_warn(napi->dev, "Unable to set IRQ notifier (%d)\n",
+				    rc);
 	}
 }
 EXPORT_SYMBOL(netif_napi_set_irq_locked);
@@ -6988,6 +7014,10 @@ static void napi_restore_config(struct napi_struct *n)
 	n->defer_hard_irqs = n->config->defer_hard_irqs;
 	n->gro_flush_timeout = n->config->gro_flush_timeout;
 	n->irq_suspend_timeout = n->config->irq_suspend_timeout;
+
+	if (n->irq > 0 && n->dev->irq_affinity_auto)
+		irq_set_affinity(n->irq, &n->config->affinity_mask);
+
 	/* a NAPI ID might be stored in the config, if so use it. if not, use
 	 * napi_hash_add to generate one for us.
 	 */
@@ -7112,7 +7142,8 @@ void napi_disable_locked(struct napi_struct *n)
 	else
 		napi_hash_del(n);
 
-	if (n->irq > 0 && n->dev->rx_cpu_rmap_auto)
+	if (n->irq > 0 &&
+	    (n->dev->irq_affinity_auto || n->dev->rx_cpu_rmap_auto))
 		irq_set_affinity_notifier(n->irq, NULL);
 
 	clear_bit(NAPI_STATE_DISABLE, &n->state);
@@ -11550,9 +11581,9 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 		void (*setup)(struct net_device *),
 		unsigned int txqs, unsigned int rxqs)
 {
+	unsigned int maxqs, i, numa;
 	struct net_device *dev;
 	size_t napi_config_sz;
-	unsigned int maxqs;
 
 	BUG_ON(strlen(name) >= sizeof(dev->name));
 
@@ -11654,6 +11685,11 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 	if (!dev->napi_config)
 		goto free_all;
 
+	numa = dev_to_node(&dev->dev);
+	for (i = 0; i < maxqs; i++)
+		cpumask_set_cpu(cpumask_local_spread(i, numa),
+				&dev->napi_config[i].affinity_mask);
+
 	strscpy(dev->name, name);
 	dev->name_assign_type = name_assign_type;
 	dev->group = INIT_NETDEV_GROUP;
-- 
2.43.0


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