Skip to content

Commit

Permalink
net: Add support for XPS with QoS via traffic classes
Browse files Browse the repository at this point in the history 
This patch adds support for setting and using XPS when QoS via traffic
classes is enabled.  With this change we will factor in the priority and
traffic class mapping of the packet and use that information to correctly
select the queue.

This allows us to define a set of queues for a given traffic class via
mqprio and then configure the XPS mapping for those queues so that the
traffic flows can avoid head-of-line blocking between the individual CPUs
if so desired.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
Alexander Duyck authored and David S. Miller committed Oct 31, 2016
1 parent 6234f87 commit 184c449
Show file tree
Hide file tree
Showing 3 changed files with 105 additions and 47 deletions.
4 changes: 2 additions & 2 deletions include/linux/netdevice.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -732,8 +732,8 @@ struct xps_dev_maps {
struct rcu_head rcu;
struct xps_map __rcu *cpu_map[0];
};
#define XPS_DEV_MAPS_SIZE (sizeof(struct xps_dev_maps) + \
(nr_cpu_ids * sizeof(struct xps_map *)))
#define XPS_DEV_MAPS_SIZE(_tcs) (sizeof(struct xps_dev_maps) + \
(nr_cpu_ids * (_tcs) * sizeof(struct xps_map *)))
#endif /* CONFIG_XPS */

#define TC_MAX_QUEUE 16
Expand Down
117 changes: 83 additions & 34 deletions net/core/dev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2002,14 +2002,22 @@ static bool remove_xps_queue_cpu(struct net_device *dev,
struct xps_dev_maps *dev_maps,
int cpu, u16 offset, u16 count)
{
int i, j;
int num_tc = dev->num_tc ? : 1;
bool active = false;
int tci;

for (i = count, j = offset; i--; j++) {
if (!remove_xps_queue(dev_maps, cpu, j))
break;
for (tci = cpu * num_tc; num_tc--; tci++) {
int i, j;

for (i = count, j = offset; i--; j++) {
if (!remove_xps_queue(dev_maps, cpu, j))
break;
}

active |= i < 0;
}

return i < 0;
return active;
}

static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
Expand Down Expand Up @@ -2086,46 +2094,67 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
u16 index)
{
struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
int i, cpu, tci, numa_node_id = -2;
int maps_sz, num_tc = 1, tc = 0;
struct xps_map *map, *new_map;
int maps_sz = max_t(unsigned int, XPS_DEV_MAPS_SIZE, L1_CACHE_BYTES);
int cpu, numa_node_id = -2;
bool active = false;

if (dev->num_tc) {
num_tc = dev->num_tc;
tc = netdev_txq_to_tc(dev, index);
if (tc < 0)
return -EINVAL;
}

maps_sz = XPS_DEV_MAPS_SIZE(num_tc);
if (maps_sz < L1_CACHE_BYTES)
maps_sz = L1_CACHE_BYTES;

mutex_lock(&xps_map_mutex);

dev_maps = xmap_dereference(dev->xps_maps);

/* allocate memory for queue storage */
for_each_online_cpu(cpu) {
if (!cpumask_test_cpu(cpu, mask))
continue;

for_each_cpu_and(cpu, cpu_online_mask, mask) {
if (!new_dev_maps)
new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
if (!new_dev_maps) {
mutex_unlock(&xps_map_mutex);
return -ENOMEM;
}

map = dev_maps ? xmap_dereference(dev_maps->cpu_map[cpu]) :
tci = cpu * num_tc + tc;
map = dev_maps ? xmap_dereference(dev_maps->cpu_map[tci]) :
NULL;

map = expand_xps_map(map, cpu, index);
if (!map)
goto error;

RCU_INIT_POINTER(new_dev_maps->cpu_map[cpu], map);
RCU_INIT_POINTER(new_dev_maps->cpu_map[tci], map);
}

if (!new_dev_maps)
goto out_no_new_maps;

for_each_possible_cpu(cpu) {
/* copy maps belonging to foreign traffic classes */
for (i = tc, tci = cpu * num_tc; dev_maps && i--; tci++) {
/* fill in the new device map from the old device map */
map = xmap_dereference(dev_maps->cpu_map[tci]);
RCU_INIT_POINTER(new_dev_maps->cpu_map[tci], map);
}

/* We need to explicitly update tci as prevous loop
* could break out early if dev_maps is NULL.
*/
tci = cpu * num_tc + tc;

if (cpumask_test_cpu(cpu, mask) && cpu_online(cpu)) {
/* add queue to CPU maps */
int pos = 0;

map = xmap_dereference(new_dev_maps->cpu_map[cpu]);
map = xmap_dereference(new_dev_maps->cpu_map[tci]);
while ((pos < map->len) && (map->queues[pos] != index))
pos++;

Expand All @@ -2139,26 +2168,36 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
#endif
} else if (dev_maps) {
/* fill in the new device map from the old device map */
map = xmap_dereference(dev_maps->cpu_map[cpu]);
RCU_INIT_POINTER(new_dev_maps->cpu_map[cpu], map);
map = xmap_dereference(dev_maps->cpu_map[tci]);
RCU_INIT_POINTER(new_dev_maps->cpu_map[tci], map);
}

/* copy maps belonging to foreign traffic classes */
for (i = num_tc - tc, tci++; dev_maps && --i; tci++) {
/* fill in the new device map from the old device map */
map = xmap_dereference(dev_maps->cpu_map[tci]);
RCU_INIT_POINTER(new_dev_maps->cpu_map[tci], map);
}
}

rcu_assign_pointer(dev->xps_maps, new_dev_maps);

/* Cleanup old maps */
if (dev_maps) {
for_each_possible_cpu(cpu) {
new_map = xmap_dereference(new_dev_maps->cpu_map[cpu]);
map = xmap_dereference(dev_maps->cpu_map[cpu]);
if (!dev_maps)
goto out_no_old_maps;

for_each_possible_cpu(cpu) {
for (i = num_tc, tci = cpu * num_tc; i--; tci++) {
new_map = xmap_dereference(new_dev_maps->cpu_map[tci]);
map = xmap_dereference(dev_maps->cpu_map[tci]);
if (map && map != new_map)
kfree_rcu(map, rcu);
}

kfree_rcu(dev_maps, rcu);
}

kfree_rcu(dev_maps, rcu);

out_no_old_maps:
dev_maps = new_dev_maps;
active = true;

Expand All @@ -2173,11 +2212,12 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,

/* removes queue from unused CPUs */
for_each_possible_cpu(cpu) {
if (cpumask_test_cpu(cpu, mask) && cpu_online(cpu))
continue;

if (remove_xps_queue(dev_maps, cpu, index))
active = true;
for (i = tc, tci = cpu * num_tc; i--; tci++)
active |= remove_xps_queue(dev_maps, tci, index);
if (!cpumask_test_cpu(cpu, mask) || !cpu_online(cpu))
active |= remove_xps_queue(dev_maps, tci, index);
for (i = num_tc - tc, tci++; --i; tci++)
active |= remove_xps_queue(dev_maps, tci, index);
}

/* free map if not active */
Expand All @@ -2193,11 +2233,14 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
error:
/* remove any maps that we added */
for_each_possible_cpu(cpu) {
new_map = xmap_dereference(new_dev_maps->cpu_map[cpu]);
map = dev_maps ? xmap_dereference(dev_maps->cpu_map[cpu]) :
NULL;
if (new_map && new_map != map)
kfree(new_map);
for (i = num_tc, tci = cpu * num_tc; i--; tci++) {
new_map = xmap_dereference(new_dev_maps->cpu_map[tci]);
map = dev_maps ?
xmap_dereference(dev_maps->cpu_map[tci]) :
NULL;
if (new_map && new_map != map)
kfree(new_map);
}
}

mutex_unlock(&xps_map_mutex);
Expand Down Expand Up @@ -3158,8 +3201,14 @@ static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
rcu_read_lock();
dev_maps = rcu_dereference(dev->xps_maps);
if (dev_maps) {
map = rcu_dereference(
dev_maps->cpu_map[skb->sender_cpu - 1]);
unsigned int tci = skb->sender_cpu - 1;

if (dev->num_tc) {
tci *= dev->num_tc;
tci += netdev_get_prio_tc_map(dev, skb->priority);
}

map = rcu_dereference(dev_maps->cpu_map[tci]);
if (map) {
if (map->len == 1)
queue_index = map->queues[0];
Expand Down
31 changes: 20 additions & 11 deletions net/core/net-sysfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1210,29 +1210,38 @@ static ssize_t show_xps_map(struct netdev_queue *queue,
struct netdev_queue_attribute *attribute, char *buf)
{
struct net_device *dev = queue->dev;
int cpu, len, num_tc = 1, tc = 0;
struct xps_dev_maps *dev_maps;
cpumask_var_t mask;
unsigned long index;
int i, len;

if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
return -ENOMEM;

index = get_netdev_queue_index(queue);

if (dev->num_tc) {
num_tc = dev->num_tc;
tc = netdev_txq_to_tc(dev, index);
if (tc < 0)
return -EINVAL;
}

rcu_read_lock();
dev_maps = rcu_dereference(dev->xps_maps);
if (dev_maps) {
for_each_possible_cpu(i) {
struct xps_map *map =
rcu_dereference(dev_maps->cpu_map[i]);
if (map) {
int j;
for (j = 0; j < map->len; j++) {
if (map->queues[j] == index) {
cpumask_set_cpu(i, mask);
break;
}
for_each_possible_cpu(cpu) {
int i, tci = cpu * num_tc + tc;
struct xps_map *map;

map = rcu_dereference(dev_maps->cpu_map[tci]);
if (!map)
continue;

for (i = map->len; i--;) {
if (map->queues[i] == index) {
cpumask_set_cpu(cpu, mask);
break;
}
}
}
Expand Down

0 comments on commit 184c449

Please sign in to comment.