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xen-netback: making the bandwidth limiter runtime settable

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With the current netback, the bandwidth limiter's parameters are only
settable during vif setup time.  This patch register a watch on them, and
thus makes them runtime changeable.

When the watch fires, the timer is reset.  The timer's mutex is used for
fencing the change.

Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: Imre Palik <imrep@amazon.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Palik, Imre 2015-03-19 11:05:42 +01:00 committed by David S. Miller
parent 750f2f9165
commit edafc132ba
4 changed files with 63 additions and 3 deletions
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4
drivers/net/xen-netback/common.h
View File

@ -238,6 +238,8 @@ struct xenvif {
unsigned int num_queues; /* active queues, resource allocated */
unsigned int stalled_queues;
struct xenbus_watch credit_watch;
spinlock_t lock;
#ifdef CONFIG_DEBUG_FS
@ -260,6 +262,8 @@ static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
return to_xenbus_device(vif->dev->dev.parent);
}
void xenvif_tx_credit_callback(unsigned long data);
struct xenvif *xenvif_alloc(struct device *parent,
domid_t domid,
unsigned int handle);

1
drivers/net/xen-netback/interface.c
View File

@ -463,6 +463,7 @@ int xenvif_init_queue(struct xenvif_queue *queue)
queue->credit_bytes = queue->remaining_credit = ~0UL;
queue->credit_usec = 0UL;
init_timer(&queue->credit_timeout);
queue->credit_timeout.function = xenvif_tx_credit_callback;
queue->credit_window_start = get_jiffies_64();
queue->rx_queue_max = XENVIF_RX_QUEUE_BYTES;

4
drivers/net/xen-netback/netback.c
View File

@ -641,7 +641,7 @@ static void tx_add_credit(struct xenvif_queue *queue)
queue->remaining_credit = min(max_credit, max_burst);
}
static void tx_credit_callback(unsigned long data)
void xenvif_tx_credit_callback(unsigned long data)
{
struct xenvif_queue *queue = (struct xenvif_queue *)data;
tx_add_credit(queue);
@ -1169,8 +1169,6 @@ static bool tx_credit_exceeded(struct xenvif_queue *queue, unsigned size)
if (size > queue->remaining_credit) {
queue->credit_timeout.data =
(unsigned long)queue;
queue->credit_timeout.function =
tx_credit_callback;
mod_timer(&queue->credit_timeout,
next_credit);
queue->credit_window_start = next_credit;

57
drivers/net/xen-netback/xenbus.c
View File

@ -41,6 +41,7 @@ static void connect(struct backend_info *be);
static int read_xenbus_vif_flags(struct backend_info *be);
static int backend_create_xenvif(struct backend_info *be);
static void unregister_hotplug_status_watch(struct backend_info *be);
static void xen_unregister_watchers(struct xenvif *vif);
static void set_backend_state(struct backend_info *be,
enum xenbus_state state);
@ -232,6 +233,7 @@ static int netback_remove(struct xenbus_device *dev)
unregister_hotplug_status_watch(be);
if (be->vif) {
kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
xen_unregister_watchers(be->vif);
xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
xenvif_free(be->vif);
be->vif = NULL;
@ -430,6 +432,7 @@ static int backend_create_xenvif(struct backend_info *be)
static void backend_disconnect(struct backend_info *be)
{
if (be->vif) {
xen_unregister_watchers(be->vif);
#ifdef CONFIG_DEBUG_FS
xenvif_debugfs_delif(be->vif);
#endif /* CONFIG_DEBUG_FS */
@ -645,6 +648,59 @@ static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
return 0;
}
static void xen_net_rate_changed(struct xenbus_watch *watch,
const char **vec, unsigned int len)
{
struct xenvif *vif = container_of(watch, struct xenvif, credit_watch);
struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
unsigned long credit_bytes;
unsigned long credit_usec;
unsigned int queue_index;
xen_net_read_rate(dev, &credit_bytes, &credit_usec);
for (queue_index = 0; queue_index < vif->num_queues; queue_index++) {
struct xenvif_queue *queue = &vif->queues[queue_index];
queue->credit_bytes = credit_bytes;
queue->credit_usec = credit_usec;
if (!mod_timer_pending(&queue->credit_timeout, jiffies) &&
queue->remaining_credit > queue->credit_bytes) {
queue->remaining_credit = queue->credit_bytes;
}
}
}
static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
{
int err = 0;
char *node;
unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
node = kmalloc(maxlen, GFP_KERNEL);
if (!node)
return -ENOMEM;
snprintf(node, maxlen, "%s/rate", dev->nodename);
vif->credit_watch.node = node;
vif->credit_watch.callback = xen_net_rate_changed;
err = register_xenbus_watch(&vif->credit_watch);
if (err) {
pr_err("Failed to set watcher %s\n", vif->credit_watch.node);
kfree(node);
vif->credit_watch.node = NULL;
vif->credit_watch.callback = NULL;
}
return err;
}
static void xen_unregister_watchers(struct xenvif *vif)
{
if (vif->credit_watch.node) {
unregister_xenbus_watch(&vif->credit_watch);
kfree(vif->credit_watch.node);
vif->credit_watch.node = NULL;
}
}
static void unregister_hotplug_status_watch(struct backend_info *be)
{
if (be->have_hotplug_status_watch) {
@ -709,6 +765,7 @@ static void connect(struct backend_info *be)
}
xen_net_read_rate(dev, &credit_bytes, &credit_usec);
xen_register_watchers(dev, be->vif);
read_xenbus_vif_flags(be);
/* Use the number of queues requested by the frontend */