From e1f00a69ec26e3eb9847c61c665b8fb3f0c6b477 Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Wed, 22 May 2013 06:34:45 +0000 Subject: [PATCH] xen-netback: split event channels support for Xen backend driver Netback and netfront only use one event channel to do TX / RX notification, which may cause unnecessary wake-up of processing routines. This patch adds a new feature called feature-split-event-channels to netback, enabling it to handle TX and RX events separately. Netback will use tx_irq to notify guest for TX completion, rx_irq for RX notification. If frontend doesn't support this feature, tx_irq equals to rx_irq. Signed-off-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/common.h | 13 ++++-- drivers/net/xen-netback/interface.c | 85 ++++++++++++++++++++++++++++++------- drivers/net/xen-netback/netback.c | 14 ++++-- drivers/net/xen-netback/xenbus.c | 41 +++++++++++++++--- 4 files changed, 124 insertions(+), 29 deletions(-) diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 6102a6c..8a4d77e 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -57,8 +57,12 @@ struct xenvif { u8 fe_dev_addr[6]; - /* Physical parameters of the comms window. */ - unsigned int irq; + /* When feature-split-event-channels = 0, tx_irq = rx_irq. */ + unsigned int tx_irq; + unsigned int rx_irq; + /* Only used when feature-split-event-channels = 1 */ + char tx_irq_name[IFNAMSIZ+4]; /* DEVNAME-tx */ + char rx_irq_name[IFNAMSIZ+4]; /* DEVNAME-rx */ /* List of frontends to notify after a batch of frames sent. */ struct list_head notify_list; @@ -113,7 +117,8 @@ struct xenvif *xenvif_alloc(struct device *parent, unsigned int handle); int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, - unsigned long rx_ring_ref, unsigned int evtchn); + unsigned long rx_ring_ref, unsigned int tx_evtchn, + unsigned int rx_evtchn); void xenvif_disconnect(struct xenvif *vif); void xenvif_get(struct xenvif *vif); @@ -158,4 +163,6 @@ void xenvif_carrier_off(struct xenvif *vif); /* Returns number of ring slots required to send an skb to the frontend */ unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb); +extern bool separate_tx_rx_irq; + #endif /* __XEN_NETBACK__COMMON_H__ */ diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 82202c2..087d2db 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -60,21 +60,39 @@ static int xenvif_rx_schedulable(struct xenvif *vif) return xenvif_schedulable(vif) && !xen_netbk_rx_ring_full(vif); } -static irqreturn_t xenvif_interrupt(int irq, void *dev_id) +static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id) { struct xenvif *vif = dev_id; if (vif->netbk == NULL) - return IRQ_NONE; + return IRQ_HANDLED; xen_netbk_schedule_xenvif(vif); + return IRQ_HANDLED; +} + +static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id) +{ + struct xenvif *vif = dev_id; + + if (vif->netbk == NULL) + return IRQ_HANDLED; + if (xenvif_rx_schedulable(vif)) netif_wake_queue(vif->dev); return IRQ_HANDLED; } +static irqreturn_t xenvif_interrupt(int irq, void *dev_id) +{ + xenvif_tx_interrupt(irq, dev_id); + xenvif_rx_interrupt(irq, dev_id); + + return IRQ_HANDLED; +} + static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct xenvif *vif = netdev_priv(dev); @@ -125,13 +143,17 @@ static struct net_device_stats *xenvif_get_stats(struct net_device *dev) static void xenvif_up(struct xenvif *vif) { xen_netbk_add_xenvif(vif); - enable_irq(vif->irq); + enable_irq(vif->tx_irq); + if (vif->tx_irq != vif->rx_irq) + enable_irq(vif->rx_irq); xen_netbk_check_rx_xenvif(vif); } static void xenvif_down(struct xenvif *vif) { - disable_irq(vif->irq); + disable_irq(vif->tx_irq); + if (vif->tx_irq != vif->rx_irq) + disable_irq(vif->rx_irq); del_timer_sync(&vif->credit_timeout); xen_netbk_deschedule_xenvif(vif); xen_netbk_remove_xenvif(vif); @@ -308,12 +330,13 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, } int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, - unsigned long rx_ring_ref, unsigned int evtchn) + unsigned long rx_ring_ref, unsigned int tx_evtchn, + unsigned int rx_evtchn) { int err = -ENOMEM; /* Already connected through? */ - if (vif->irq) + if (vif->tx_irq) return 0; __module_get(THIS_MODULE); @@ -322,13 +345,37 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, if (err < 0) goto err; - err = bind_interdomain_evtchn_to_irqhandler( - vif->domid, evtchn, xenvif_interrupt, 0, - vif->dev->name, vif); - if (err < 0) - goto err_unmap; - vif->irq = err; - disable_irq(vif->irq); + if (tx_evtchn == rx_evtchn) { + /* feature-split-event-channels == 0 */ + err = bind_interdomain_evtchn_to_irqhandler( + vif->domid, tx_evtchn, xenvif_interrupt, 0, + vif->dev->name, vif); + if (err < 0) + goto err_unmap; + vif->tx_irq = vif->rx_irq = err; + disable_irq(vif->tx_irq); + } else { + /* feature-split-event-channels == 1 */ + snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name), + "%s-tx", vif->dev->name); + err = bind_interdomain_evtchn_to_irqhandler( + vif->domid, tx_evtchn, xenvif_tx_interrupt, 0, + vif->tx_irq_name, vif); + if (err < 0) + goto err_unmap; + vif->tx_irq = err; + disable_irq(vif->tx_irq); + + snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name), + "%s-rx", vif->dev->name); + err = bind_interdomain_evtchn_to_irqhandler( + vif->domid, rx_evtchn, xenvif_rx_interrupt, 0, + vif->rx_irq_name, vif); + if (err < 0) + goto err_tx_unbind; + vif->rx_irq = err; + disable_irq(vif->rx_irq); + } xenvif_get(vif); @@ -342,6 +389,9 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, rtnl_unlock(); return 0; +err_tx_unbind: + unbind_from_irqhandler(vif->tx_irq, vif); + vif->tx_irq = 0; err_unmap: xen_netbk_unmap_frontend_rings(vif); err: @@ -375,8 +425,13 @@ void xenvif_disconnect(struct xenvif *vif) atomic_dec(&vif->refcnt); wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0); - if (vif->irq) { - unbind_from_irqhandler(vif->irq, vif); + if (vif->tx_irq) { + if (vif->tx_irq == vif->rx_irq) + unbind_from_irqhandler(vif->tx_irq, vif); + else { + unbind_from_irqhandler(vif->tx_irq, vif); + unbind_from_irqhandler(vif->rx_irq, vif); + } /* vif->irq is valid, we had a module_get in * xenvif_connect. */ diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 2d9477f..82576ff 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -47,6 +47,13 @@ #include #include +/* Provide an option to disable split event channels at load time as + * event channels are limited resource. Split event channels are + * enabled by default. + */ +bool separate_tx_rx_irq = 1; +module_param(separate_tx_rx_irq, bool, 0644); + /* * This is the maximum slots a skb can have. If a guest sends a skb * which exceeds this limit it is considered malicious. @@ -662,7 +669,7 @@ static void xen_netbk_rx_action(struct xen_netbk *netbk) { struct xenvif *vif = NULL, *tmp; s8 status; - u16 irq, flags; + u16 flags; struct xen_netif_rx_response *resp; struct sk_buff_head rxq; struct sk_buff *skb; @@ -771,7 +778,6 @@ static void xen_netbk_rx_action(struct xen_netbk *netbk) sco->meta_slots_used); RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret); - irq = vif->irq; if (ret && list_empty(&vif->notify_list)) list_add_tail(&vif->notify_list, ¬ify); @@ -783,7 +789,7 @@ static void xen_netbk_rx_action(struct xen_netbk *netbk) } list_for_each_entry_safe(vif, tmp, ¬ify, notify_list) { - notify_remote_via_irq(vif->irq); + notify_remote_via_irq(vif->rx_irq); list_del_init(&vif->notify_list); } @@ -1762,7 +1768,7 @@ static void make_tx_response(struct xenvif *vif, vif->tx.rsp_prod_pvt = ++i; RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->tx, notify); if (notify) - notify_remote_via_irq(vif->irq); + notify_remote_via_irq(vif->tx_irq); } static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif, diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index d230c14..04bd860 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -122,6 +122,16 @@ static int netback_probe(struct xenbus_device *dev, goto fail; } + /* + * Split event channels support, this is optional so it is not + * put inside the above loop. + */ + err = xenbus_printf(XBT_NIL, dev->nodename, + "feature-split-event-channels", + "%u", separate_tx_rx_irq); + if (err) + pr_debug("Error writing feature-split-event-channels"); + err = xenbus_switch_state(dev, XenbusStateInitWait); if (err) goto fail; @@ -393,21 +403,36 @@ static int connect_rings(struct backend_info *be) struct xenvif *vif = be->vif; struct xenbus_device *dev = be->dev; unsigned long tx_ring_ref, rx_ring_ref; - unsigned int evtchn, rx_copy; + unsigned int tx_evtchn, rx_evtchn, rx_copy; int err; int val; err = xenbus_gather(XBT_NIL, dev->otherend, "tx-ring-ref", "%lu", &tx_ring_ref, - "rx-ring-ref", "%lu", &rx_ring_ref, - "event-channel", "%u", &evtchn, NULL); + "rx-ring-ref", "%lu", &rx_ring_ref, NULL); if (err) { xenbus_dev_fatal(dev, err, - "reading %s/ring-ref and event-channel", + "reading %s/ring-ref", dev->otherend); return err; } + /* Try split event channels first, then single event channel. */ + err = xenbus_gather(XBT_NIL, dev->otherend, + "event-channel-tx", "%u", &tx_evtchn, + "event-channel-rx", "%u", &rx_evtchn, NULL); + if (err < 0) { + err = xenbus_scanf(XBT_NIL, dev->otherend, + "event-channel", "%u", &tx_evtchn); + if (err < 0) { + xenbus_dev_fatal(dev, err, + "reading %s/event-channel(-tx/rx)", + dev->otherend); + return err; + } + rx_evtchn = tx_evtchn; + } + err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u", &rx_copy); if (err == -ENOENT) { @@ -454,11 +479,13 @@ static int connect_rings(struct backend_info *be) vif->csum = !val; /* Map the shared frame, irq etc. */ - err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref, evtchn); + err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref, + tx_evtchn, rx_evtchn); if (err) { xenbus_dev_fatal(dev, err, - "mapping shared-frames %lu/%lu port %u", - tx_ring_ref, rx_ring_ref, evtchn); + "mapping shared-frames %lu/%lu port tx %u rx %u", + tx_ring_ref, rx_ring_ref, + tx_evtchn, rx_evtchn); return err; } return 0; -- 2.7.4