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Message-ID: <CALx6S36F=6R12O6Xb-WfhruOQN7S6QjOite7PVW2JqNK5BtWYg@mail.gmail.com>
Date: Thu, 27 Oct 2016 19:38:22 -0700
From: Tom Herbert <tom@...bertland.com>
To: Alexander Duyck <alexander.h.duyck@...el.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
John Fastabend <john.r.fastabend@...el.com>,
intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [net-next PATCH 3/3] net: Add support for XPS with QoS via
traffic classes
On Thu, Oct 27, 2016 at 8:40 AM, Alexander Duyck
<alexander.h.duyck@...el.com> wrote:
> 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.
>
Does this change the sys API for XPS? Is it up the user to know which
are priority queues in sys?
Thanks,
Tom
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> ---
> include/linux/netdevice.h | 5 +-
> net/core/dev.c | 136 +++++++++++++++++++++++++++++++++------------
> net/core/net-sysfs.c | 31 +++++++---
> 3 files changed, 122 insertions(+), 50 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index d045432..56f90f7 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -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
> @@ -1920,6 +1920,7 @@ int netdev_set_prio_tc_map(struct net_device *dev, u8 prio, u8 tc)
> return 0;
> }
>
> +int netdev_txq_to_tc(struct net_device *dev, unsigned int txq);
> void netdev_reset_tc(struct net_device *dev);
> int netdev_set_tc_queue(struct net_device *dev, u8 tc, u16 count, u16 offset);
> int netdev_set_num_tc(struct net_device *dev, u8 num_tc);
> diff --git a/net/core/dev.c b/net/core/dev.c
> index d124081..37c1096 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1948,6 +1948,23 @@ static void netif_setup_tc(struct net_device *dev, unsigned int txq)
> }
> }
>
> +int netdev_txq_to_tc(struct net_device *dev, unsigned int txq)
> +{
> + if (dev->num_tc) {
> + struct netdev_tc_txq *tc = &dev->tc_to_txq[0];
> + int i;
> +
> + for (i = 0; i < TC_MAX_QUEUE; i++, tc++) {
> + if ((txq - tc->offset) < tc->count)
> + return i;
> + }
> +
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> #ifdef CONFIG_XPS
> static DEFINE_MUTEX(xps_map_mutex);
> #define xmap_dereference(P) \
> @@ -1985,18 +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 tc = dev->num_tc ? : 1;
> bool active = false;
> - int i;
> + int tci;
>
> count += offset;
> - i = count;
>
> - do {
> - if (i-- == offset) {
> - active = true;
> - break;
> - }
> - } while (remove_xps_queue(dev_maps, cpu, i));
> + for (tci = cpu * tc; tc--; tci++) {
> + int i = count;
> +
> + do {
> + if (i-- == offset) {
> + active = true;
> + break;
> + }
> + } while (remove_xps_queue(dev_maps, tci, i));
> + }
>
> return active;
> }
> @@ -2075,20 +2096,28 @@ 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) {
> @@ -2096,25 +2125,35 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
> 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 */
> + tci = cpu * num_tc;
> + for (i = 0; dev_maps && i < tc; 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);
> + }
> +
> + 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++;
>
> @@ -2128,26 +2167,37 @@ 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 = tc, tci++; dev_maps && (++i < num_tc); 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) {
> + tci = cpu * num_tc;
> + for (i = 0; i < 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;
>
> @@ -2162,11 +2212,13 @@ 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;
> + tci = cpu * num_tc;
> + for (i = 0; i < 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 = tc, tci++; ++i < num_tc; tci++)
> + active |= remove_xps_queue(dev_maps, tci, index);
> }
>
> /* free map if not active */
> @@ -2182,11 +2234,15 @@ 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);
> + tci = cpu * num_tc;
> + for (i = 0; i < 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);
> @@ -3146,8 +3202,14 @@ 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];
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 6e4f347..763c1e1 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -1190,29 +1190,38 @@ 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;
> }
> }
> }
>
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