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Date: Tue, 21 May 2013 19:35:09 +0100
From: Wei Liu <wei.liu2@...rix.com>
To: <xen-devel@...ts.xen.org>, <netdev@...r.kernel.org>
CC: <ian.campbell@...rix.com>, <konrad.wilk@...cle.com>,
<david.vrabel@...rix.com>, Wei Liu <wei.liu2@...rix.com>
Subject: [PATCH net-next V2 1/2] 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 <wei.liu2@...rix.com>
---
drivers/net/xen-netback/common.h | 13 ++++--
drivers/net/xen-netback/interface.c | 84 ++++++++++++++++++++++++++++-------
drivers/net/xen-netback/netback.c | 14 ++++--
drivers/net/xen-netback/xenbus.c | 40 ++++++++++++++---
4 files changed, 122 insertions(+), 29 deletions(-)
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 6102a6c..1ae2932 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 unsigned int feature_split_event_channels;
+
#endif /* __XEN_NETBACK__COMMON_H__ */
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 82202c2..59d5b45 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 +143,15 @@ 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);
+ 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);
+ disable_irq(vif->rx_irq);
del_timer_sync(&vif->credit_timeout);
xen_netbk_deschedule_xenvif(vif);
xen_netbk_remove_xenvif(vif);
@@ -308,12 +328,13 @@ 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 +343,38 @@ 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);
+ disable_irq(vif->rx_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 +388,9 @@ 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 +424,13 @@ 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..ccfbb74 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -47,6 +47,13 @@
#include <asm/xen/hypercall.h>
#include <asm/xen/page.h>
+/* Provide an option to disable split event channels at load time as
+ * event channels are limited resource. Split event channels are
+ * enabled by default.
+ */
+unsigned int feature_split_event_channels = 1;
+module_param(feature_split_event_channels, uint, 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..461efc6 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -114,6 +114,15 @@ static int netback_probe(struct xenbus_device *dev,
goto abort_transaction;
}
+ /* Split event channels support */
+ err = xenbus_printf(xbt, dev->nodename,
+ "feature-split-event-channels",
+ "%u", feature_split_event_channels);
+ if (err) {
+ message = "writing feature-split-event-channels";
+ goto abort_transaction;
+ }
+
err = xenbus_transaction_end(xbt, 0);
} while (err == -EAGAIN);
@@ -393,21 +402,36 @@ 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) {
+ err = xenbus_gather(XBT_NIL, dev->otherend,
+ "event-channel", "%u", &tx_evtchn, NULL);
+ if (err) {
+ 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 +478,13 @@ 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;
--
1.7.10.4
--
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