From: Alexander Duyck Date: Wed, 10 Dec 2014 03:40:49 +0000 (-0800) Subject: net: Pull out core bits of __netdev_alloc_skb and add __napi_alloc_skb X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=fd11a83dd3630ec6a60f8a702446532c5c7e1991;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git net: Pull out core bits of __netdev_alloc_skb and add __napi_alloc_skb This change pulls the core functionality out of __netdev_alloc_skb and places them in a new function named __alloc_rx_skb. The reason for doing this is to make these bits accessible to a new function __napi_alloc_skb. In addition __alloc_rx_skb now has a new flags value that is used to determine which page frag pool to allocate from. If the SKB_ALLOC_NAPI flag is set then the NAPI pool is used. The advantage of this is that we do not have to use local_irq_save/restore when accessing the NAPI pool from NAPI context. In my test setup I saw at least 11ns of savings using the napi_alloc_skb function versus the netdev_alloc_skb function, most of this being due to the fact that we didn't have to call local_irq_save/restore. The main use case for napi_alloc_skb would be for things such as copybreak or page fragment based receive paths where an skb is allocated after the data has been received instead of before. Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 736cc99f3f6c..85ab7d72b54c 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -151,6 +151,7 @@ struct net_device; struct scatterlist; struct pipe_inode_info; struct iov_iter; +struct napi_struct; #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) struct nf_conntrack { @@ -673,6 +674,7 @@ struct sk_buff { #define SKB_ALLOC_FCLONE 0x01 #define SKB_ALLOC_RX 0x02 +#define SKB_ALLOC_NAPI 0x04 /* Returns true if the skb was allocated from PFMEMALLOC reserves */ static inline bool skb_pfmemalloc(const struct sk_buff *skb) @@ -2165,6 +2167,13 @@ static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev, } void *napi_alloc_frag(unsigned int fragsz); +struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, + unsigned int length, gfp_t gfp_mask); +static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi, + unsigned int length) +{ + return __napi_alloc_skb(napi, length, GFP_ATOMIC); +} /** * __dev_alloc_pages - allocate page for network Rx diff --git a/net/core/dev.c b/net/core/dev.c index 3f191da383f6..80f798da3d9f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4172,7 +4172,7 @@ struct sk_buff *napi_get_frags(struct napi_struct *napi) struct sk_buff *skb = napi->skb; if (!skb) { - skb = netdev_alloc_skb_ip_align(napi->dev, GRO_MAX_HEAD); + skb = napi_alloc_skb(napi, GRO_MAX_HEAD); napi->skb = skb; } return skb; diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 56ed17cd2151..ae13ef6b3ea7 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -444,10 +444,13 @@ void *napi_alloc_frag(unsigned int fragsz) EXPORT_SYMBOL(napi_alloc_frag); /** - * __netdev_alloc_skb - allocate an skbuff for rx on a specific device - * @dev: network device to receive on + * __alloc_rx_skb - allocate an skbuff for rx * @length: length to allocate * @gfp_mask: get_free_pages mask, passed to alloc_skb + * @flags: If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for + * allocations in case we have to fallback to __alloc_skb() + * If SKB_ALLOC_NAPI is set, page fragment will be allocated + * from napi_cache instead of netdev_cache. * * Allocate a new &sk_buff and assign it a usage count of one. The * buffer has unspecified headroom built in. Users should allocate @@ -456,11 +459,11 @@ EXPORT_SYMBOL(napi_alloc_frag); * * %NULL is returned if there is no free memory. */ -struct sk_buff *__netdev_alloc_skb(struct net_device *dev, - unsigned int length, gfp_t gfp_mask) +static struct sk_buff *__alloc_rx_skb(unsigned int length, gfp_t gfp_mask, + int flags) { struct sk_buff *skb = NULL; - unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) + + unsigned int fragsz = SKB_DATA_ALIGN(length) + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); if (fragsz <= PAGE_SIZE && !(gfp_mask & (__GFP_WAIT | GFP_DMA))) { @@ -469,7 +472,9 @@ struct sk_buff *__netdev_alloc_skb(struct net_device *dev, if (sk_memalloc_socks()) gfp_mask |= __GFP_MEMALLOC; - data = __netdev_alloc_frag(fragsz, gfp_mask); + data = (flags & SKB_ALLOC_NAPI) ? + __napi_alloc_frag(fragsz, gfp_mask) : + __netdev_alloc_frag(fragsz, gfp_mask); if (likely(data)) { skb = build_skb(data, fragsz); @@ -477,17 +482,72 @@ struct sk_buff *__netdev_alloc_skb(struct net_device *dev, put_page(virt_to_head_page(data)); } } else { - skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, + skb = __alloc_skb(length, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE); } + return skb; +} + +/** + * __netdev_alloc_skb - allocate an skbuff for rx on a specific device + * @dev: network device to receive on + * @length: length to allocate + * @gfp_mask: get_free_pages mask, passed to alloc_skb + * + * Allocate a new &sk_buff and assign it a usage count of one. The + * buffer has NET_SKB_PAD headroom built in. Users should allocate + * the headroom they think they need without accounting for the + * built in space. The built in space is used for optimisations. + * + * %NULL is returned if there is no free memory. + */ +struct sk_buff *__netdev_alloc_skb(struct net_device *dev, + unsigned int length, gfp_t gfp_mask) +{ + struct sk_buff *skb; + + length += NET_SKB_PAD; + skb = __alloc_rx_skb(length, gfp_mask, 0); + if (likely(skb)) { skb_reserve(skb, NET_SKB_PAD); skb->dev = dev; } + return skb; } EXPORT_SYMBOL(__netdev_alloc_skb); +/** + * __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance + * @napi: napi instance this buffer was allocated for + * @length: length to allocate + * @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages + * + * Allocate a new sk_buff for use in NAPI receive. This buffer will + * attempt to allocate the head from a special reserved region used + * only for NAPI Rx allocation. By doing this we can save several + * CPU cycles by avoiding having to disable and re-enable IRQs. + * + * %NULL is returned if there is no free memory. + */ +struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, + unsigned int length, gfp_t gfp_mask) +{ + struct sk_buff *skb; + + length += NET_SKB_PAD + NET_IP_ALIGN; + skb = __alloc_rx_skb(length, gfp_mask, SKB_ALLOC_NAPI); + + if (likely(skb)) { + skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN); + skb->dev = napi->dev; + } + + return skb; +} +EXPORT_SYMBOL(__napi_alloc_skb); + void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off, int size, unsigned int truesize) {