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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH V7 net-next 6/7] xen-netfront: Add support for multiple queues
From: "Andrew J. Bennieston" <andrew.bennieston@xxxxxxxxxx>
Build on the refactoring of the previous patch to implement multiple
queues between xen-netfront and xen-netback.
Check XenStore for multi-queue support, and set up the rings and event
channels accordingly.
Write ring references and event channels to XenStore in a queue
hierarchy if appropriate, or flat when using only one queue.
Update the xennet_select_queue() function to choose the queue on which
to transmit a packet based on the skb hash result.
Signed-off-by: Andrew J. Bennieston <andrew.bennieston@xxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
drivers/net/xen-netfront.c | 170 ++++++++++++++++++++++++++++++++++----------
1 file changed, 134 insertions(+), 36 deletions(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index f2aa7e8..cb2905e 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -57,6 +57,12 @@
#include <xen/interface/memory.h>
#include <xen/interface/grant_table.h>
+/* Module parameters */
+static unsigned int xennet_max_queues;
+module_param_named(max_queues, xennet_max_queues, uint, 0644);
+MODULE_PARM_DESC(max_queues,
+ "Maximum number of queues per virtual interface");
+
static const struct ethtool_ops xennet_ethtool_ops;
struct netfront_cb {
@@ -565,10 +571,22 @@ static int xennet_count_skb_frag_slots(struct sk_buff
*skb)
return pages;
}
-static u16 xennet_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 xennet_select_queue(struct net_device *dev, struct sk_buff *skb,
+ void *accel_priv, select_queue_fallback_t
fallback)
{
- /* Stub for later implementation of queue selection */
- return 0;
+ unsigned int num_queues = dev->real_num_tx_queues;
+ u32 hash;
+ u16 queue_idx;
+
+ /* First, check if there is only one queue */
+ if (num_queues == 1) {
+ queue_idx = 0;
+ } else {
+ hash = skb_get_hash(skb);
+ queue_idx = hash % num_queues;
+ }
+
+ return queue_idx;
}
static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -1316,7 +1334,7 @@ static struct net_device *xennet_create_dev(struct
xenbus_device *dev)
struct net_device *netdev;
struct netfront_info *np;
- netdev = alloc_etherdev_mq(sizeof(struct netfront_info), 1);
+ netdev = alloc_etherdev_mq(sizeof(struct netfront_info),
xennet_max_queues);
if (!netdev)
return ERR_PTR(-ENOMEM);
@@ -1687,6 +1705,88 @@ static int xennet_init_queue(struct netfront_queue
*queue)
return err;
}
+static int write_queue_xenstore_keys(struct netfront_queue *queue,
+ struct xenbus_transaction *xbt, int
write_hierarchical)
+{
+ /* Write the queue-specific keys into XenStore in the traditional
+ * way for a single queue, or in a queue subkeys for multiple
+ * queues.
+ */
+ struct xenbus_device *dev = queue->info->xbdev;
+ int err;
+ const char *message;
+ char *path;
+ size_t pathsize;
+
+ /* Choose the correct place to write the keys */
+ if (write_hierarchical) {
+ pathsize = strlen(dev->nodename) + 10;
+ path = kzalloc(pathsize, GFP_KERNEL);
+ if (!path) {
+ err = -ENOMEM;
+ message = "out of memory while writing ring references";
+ goto error;
+ }
+ snprintf(path, pathsize, "%s/queue-%u",
+ dev->nodename, queue->id);
+ } else {
+ path = (char *)dev->nodename;
+ }
+
+ /* Write ring references */
+ err = xenbus_printf(*xbt, path, "tx-ring-ref", "%u",
+ queue->tx_ring_ref);
+ if (err) {
+ message = "writing tx-ring-ref";
+ goto error;
+ }
+
+ err = xenbus_printf(*xbt, path, "rx-ring-ref", "%u",
+ queue->rx_ring_ref);
+ if (err) {
+ message = "writing rx-ring-ref";
+ goto error;
+ }
+
+ /* Write event channels; taking into account both shared
+ * and split event channel scenarios.
+ */
+ if (queue->tx_evtchn == queue->rx_evtchn) {
+ /* Shared event channel */
+ err = xenbus_printf(*xbt, path,
+ "event-channel", "%u", queue->tx_evtchn);
+ if (err) {
+ message = "writing event-channel";
+ goto error;
+ }
+ } else {
+ /* Split event channels */
+ err = xenbus_printf(*xbt, path,
+ "event-channel-tx", "%u", queue->tx_evtchn);
+ if (err) {
+ message = "writing event-channel-tx";
+ goto error;
+ }
+
+ err = xenbus_printf(*xbt, path,
+ "event-channel-rx", "%u", queue->rx_evtchn);
+ if (err) {
+ message = "writing event-channel-rx";
+ goto error;
+ }
+ }
+
+ if (write_hierarchical)
+ kfree(path);
+ return 0;
+
+error:
+ if (write_hierarchical)
+ kfree(path);
+ xenbus_dev_fatal(dev, err, "%s", message);
+ return err;
+}
+
/* Common code used when first setting up, and when resuming. */
static int talk_to_netback(struct xenbus_device *dev,
struct netfront_info *info)
@@ -1696,11 +1796,19 @@ static int talk_to_netback(struct xenbus_device *dev,
int err;
unsigned int feature_split_evtchn;
unsigned int i = 0;
+ unsigned int max_queues = 0;
struct netfront_queue *queue = NULL;
unsigned int num_queues = 1;
info->netdev->irq = 0;
+ /* Check if backend supports multiple queues */
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "multi-queue-max-queues", "%u", &max_queues);
+ if (err < 0)
+ max_queues = 1;
+ num_queues = min(max_queues, xennet_max_queues);
+
/* Check feature-split-event-channels */
err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
"feature-split-event-channels", "%u",
@@ -1765,49 +1873,35 @@ static int talk_to_netback(struct xenbus_device *dev,
}
again:
- queue = &info->queues[0]; /* Use first queue only */
-
err = xenbus_transaction_start(&xbt);
if (err) {
xenbus_dev_fatal(dev, err, "starting transaction");
goto destroy_ring;
}
- err = xenbus_printf(xbt, dev->nodename, "tx-ring-ref", "%u",
- queue->tx_ring_ref);
- if (err) {
- message = "writing tx ring-ref";
- goto abort_transaction;
- }
- err = xenbus_printf(xbt, dev->nodename, "rx-ring-ref", "%u",
- queue->rx_ring_ref);
- if (err) {
- message = "writing rx ring-ref";
- goto abort_transaction;
- }
-
- if (queue->tx_evtchn == queue->rx_evtchn) {
- err = xenbus_printf(xbt, dev->nodename,
- "event-channel", "%u", queue->tx_evtchn);
- if (err) {
- message = "writing event-channel";
- goto abort_transaction;
- }
+ if (num_queues == 1) {
+ err = write_queue_xenstore_keys(&info->queues[0], &xbt, 0); /*
flat */
+ if (err)
+ goto abort_transaction_no_dev_fatal;
} else {
- err = xenbus_printf(xbt, dev->nodename,
- "event-channel-tx", "%u", queue->tx_evtchn);
+ /* Write the number of queues */
+ err = xenbus_printf(xbt, dev->nodename,
"multi-queue-num-queues",
+ "%u", num_queues);
if (err) {
- message = "writing event-channel-tx";
- goto abort_transaction;
+ message = "writing multi-queue-num-queues";
+ goto abort_transaction_no_dev_fatal;
}
- err = xenbus_printf(xbt, dev->nodename,
- "event-channel-rx", "%u", queue->rx_evtchn);
- if (err) {
- message = "writing event-channel-rx";
- goto abort_transaction;
+
+ /* Write the keys for each queue */
+ for (i = 0; i < num_queues; ++i) {
+ queue = &info->queues[i];
+ err = write_queue_xenstore_keys(queue, &xbt, 1); /*
hierarchical */
+ if (err)
+ goto abort_transaction_no_dev_fatal;
}
}
+ /* The remaining keys are not queue-specific */
err = xenbus_printf(xbt, dev->nodename, "request-rx-copy", "%u",
1);
if (err) {
@@ -1857,8 +1951,9 @@ again:
return 0;
abort_transaction:
- xenbus_transaction_end(xbt, 1);
xenbus_dev_fatal(dev, err, "%s", message);
+abort_transaction_no_dev_fatal:
+ xenbus_transaction_end(xbt, 1);
destroy_ring:
xennet_disconnect_backend(info);
kfree(info->queues);
@@ -2264,6 +2359,9 @@ static int __init netif_init(void)
pr_info("Initialising Xen virtual ethernet driver\n");
+ /* Allow as many queues as there are CPUs, by default */
+ xennet_max_queues = num_online_cpus();
+
return xenbus_register_frontend(&netfront_driver);
}
module_init(netif_init);
--
1.7.10.4
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