netdev - Re: [PATCH 2/2 v7] xps: Transmit Packet Steering

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Date:	Mon, 22 Nov 2010 14:33:56 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Tom Herbert <therbert@...gle.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH 2/2 v7] xps: Transmit Packet Steering

Le dimanche 21 novembre 2010 à 15:17 -0800, Tom Herbert a écrit :

...

> +
> +static DEFINE_MUTEX(xps_map_mutex);
> +
> +static ssize_t store_xps_map(struct netdev_queue *queue,
> +		      struct netdev_queue_attribute *attribute,
> +		      const char *buf, size_t len)
> +{
> +	struct net_device *dev = queue->dev;
> +	cpumask_var_t mask;
> +	int err, i, cpu, pos, map_len, alloc_len, need_set;
> +	unsigned long index;
> +	struct xps_map *map, *new_map;
> +	struct xps_dev_maps *dev_maps, *new_dev_maps;
> +	int nonempty = 0;
> +
> +	if (!capable(CAP_NET_ADMIN))
> +		return -EPERM;
> +
> +	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	index = get_netdev_queue_index(queue);
> +
> +	err = bitmap_parse(buf, len, cpumask_bits(mask), nr_cpumask_bits);
> +	if (err) {
> +		free_cpumask_var(mask);
> +		return err;
> +	}
> +
> +	new_dev_maps = kzalloc(max_t(unsigned,
> +	    XPS_DEV_MAPS_SIZE, L1_CACHE_BYTES), GFP_KERNEL);
> +	if (!new_dev_maps) {
> +		free_cpumask_var(mask);
> +		return -ENOMEM;
> +	}
> +
> +	mutex_lock(&xps_map_mutex);
> +
> +	dev_maps = dev->xps_maps;
> +
> +	for_each_possible_cpu(cpu) {
> +		new_map = map = dev_maps ? dev_maps->cpu_map[cpu] : NULL;
> +
> +		if (map) {
> +			for (pos = 0; pos < map->len; pos++)
> +				if (map->queues[pos] == index)
> +					break;
> +			map_len = map->len;
> +			alloc_len = map->alloc_len;
> +		} else
> +			pos = map_len = alloc_len = 0;
> +
> +		need_set = cpu_isset(cpu, *mask) && cpu_online(cpu);
> +
> +		if (need_set && pos >= map_len) {
> +			/* Need to add queue to this CPU's map */
> +			if (map_len >= alloc_len) {
> +				alloc_len = alloc_len ?
> +				    2 * alloc_len : XPS_MIN_MAP_ALLOC;
> +				new_map = kzalloc(XPS_MAP_SIZE(alloc_len),
> +				    GFP_KERNEL);

		kzalloc_node(size, GFP_KERNEL, cpu_to_node(cpu)) 

to get memory close to the cpu ?

> +				if (!new_map)
> +					goto error;
> +				new_map->alloc_len = alloc_len;
> +				for (i = 0; i < map_len; i++)
> +					new_map->queues[i] = map->queues[i];
> +				new_map->len = map_len;
> +			}
> +			new_map->queues[new_map->len++] = index;
> +		} else if (!need_set && pos < map_len) {
> +			/* Need to remove queue from this CPU's map */
> +			if (map_len > 1)
> +				new_map->queues[pos] =
> +				    new_map->queues[--new_map->len];
> +			else
> +				new_map = NULL;
> +		}
> +		new_dev_maps->cpu_map[cpu] = new_map;
> +	}
> +
> +	/* Cleanup old maps */
> +	for_each_possible_cpu(cpu) {
> +		map = dev_maps ? dev_maps->cpu_map[cpu] : NULL;
> +		if (map && new_dev_maps->cpu_map[cpu] != map)
> +			call_rcu(&map->rcu, xps_map_release);
> +		if (new_dev_maps->cpu_map[cpu])
> +			nonempty = 1;
> +	}
> +

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