netdev - Re: [PATCH] rps: make distributing packets fairly among all the online CPUs default

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Date:	Tue, 23 Mar 2010 08:20:52 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	xiaosuo@...il.com
Cc:	"David S. Miller" <davem@...emloft.net>,
	Tom Herbert <therbert@...gle.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] rps: make distributing packets fairly among all the
 online CPUs default

Le mardi 23 mars 2010 à 14:24 +0800, Changli Gao a écrit :
> make distributing packets fairly among all the online CPUs default.
> 
> Make distributing packets fairly among all the online CPUs default, then
> users don't need any explicit configuration to get the benefit of RPS.
> 
> Signed-off-by: Changli Gao <xiaosuo@...il.com>
> ----
> net/core/dev.c | 34 ++++++++++++++++++++++++++++++++--
> 1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/dev.c b/net/core/dev.c
> index c0e2608..a4246f1 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5234,6 +5234,24 @@ void netif_stacked_transfer_operstate(const struct net_device *rootdev,
>  }
>  EXPORT_SYMBOL(netif_stacked_transfer_operstate);
>  
> +static struct rps_map* alloc_rps_map(void)
> +{
> +	struct rps_map *map;
> +	int i, cpu;
> +
> +	map = kzalloc(max_t(unsigned,
> +			    RPS_MAP_SIZE(cpumask_weight(cpu_online_mask)),
> +			    L1_CACHE_BYTES), GFP_KERNEL);
> +	if (map == NULL)
> +		return NULL;
> +	i = 0;
> +	for_each_online_cpu(cpu)
> +		map->cpus[i++] = cpu;
> +	map->len = i;
> +
> +	return map;
> +}
> +
>  /**
>   *	register_netdevice	- register a network device
>   *	@dev: device to register
> @@ -5282,7 +5300,13 @@ int register_netdevice(struct net_device *dev)
>  			ret = -ENOMEM;
>  			goto out;
>  		}
> -
> +		dev->_rx->rps_map = alloc_rps_map();
> +		if (dev->_rx->rps_map == NULL) {
> +			kfree(dev->_rx);
> +			dev->_rx = NULL;
> +			ret = -ENOMEM;
> +			goto out;
> +		}
>  		dev->_rx->first = dev->_rx;
>  		atomic_set(&dev->_rx->count, 1);
>  		dev->num_rx_queues = 1;
> @@ -5688,8 +5712,12 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
>  	 * Set a pointer to first element in the array which holds the
>  	 * reference count.
>  	 */
> -	for (i = 0; i < queue_count; i++)
> +	for (i = 0; i < queue_count; i++) {
>  		rx[i].first = rx;
> +		rx[i].rps_map = alloc_rps_map();
> +		if (rx[i].rps_map == NULL)
> +			goto free_rx;
> +	}
>  
>  	dev = PTR_ALIGN(p, NETDEV_ALIGN);
>  	dev->padded = (char *)dev - (char *)p;
> @@ -5723,6 +5751,8 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
>  	return dev;
>  
>  free_rx:
> +	for (i = 0; i < queue_count; i++)
> +		kfree(rx[i].rps_map);
>  	kfree(rx);
>  free_tx:
>  	kfree(tx);
> 
> 
> --

You cannot do this like this, these allocations wont be freed.

Better would be to take a look at net/core/net-sysfs.c



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