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Message-ID: <1286639996.2692.148.camel@edumazet-laptop> Date: Sat, 09 Oct 2010 17:59:56 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: Stanislaw Gruszka <sgruszka@...hat.com>, David Miller <davem@...emloft.net> Cc: Francois Romieu <romieu@...zoreil.com>, netdev@...r.kernel.org Subject: [PATCH] net: introduce alloc_skb_order0 Le vendredi 08 octobre 2010 à 18:03 +0200, Stanislaw Gruszka a écrit : > On Fri, Oct 08, 2010 at 05:04:07PM +0200, Eric Dumazet wrote: > > Switch to SLAB -> no more problem ;) > > yeh, I wish to, but fedora use SLUB because of some debugging > capabilities. Yes, of course, I was kidding :) echo 0 >/sys/kernel/slab/kmalloc-2048/order echo 0 >/sys/kernel/slab/kmalloc-1024/order echo 0 >/sys/kernel/slab/kmalloc-512/order Should do the trick : No more high order allocations for MTU=1500 frames. For MTU=9000 frames, we probably need something like this patch : (Not yet for inclusion, this is an RFC, this will need two separate patches) [PATCH] net: introduce alloc_skb_order0() Reception of big frames hit a memory allocation problem, because of high order pages allocations (order-3 sometimes for MTU=9000). This patch introduces alloc_skb_order0(), to build skbs with order-0 pages only. Their headlen is at most SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN) (3648 bytes on x86_64, 3840 bytes on x86_32) As net drivers might use skb_store_bits() to copy data to this newly allocated skb, we might even use __GFP_HIGHMEM for the fragments ? Note : Use GFP_NOWAIT | __GFP_NOWARN mask to allocate pages, since we dont want to let big packets exhaust GFP_ATOMIC pool. Signed-off-by: Eric Dumazet <eric.dumazet@...il.com> --- drivers/net/r8169.c | 19 ++++++--------- include/linux/skbuff.h | 1 net/core/skbuff.c | 47 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 56 insertions(+), 11 deletions(-) diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c index fe3b762..f4220db 100644 --- a/drivers/net/r8169.c +++ b/drivers/net/r8169.c @@ -4468,27 +4468,24 @@ static inline void rtl8169_rx_csum(struct sk_buff *skb, u32 opts1) skb_checksum_none_assert(skb); } -static inline bool rtl8169_try_rx_copy(struct sk_buff **sk_buff, +static inline bool rtl8169_try_rx_copy(struct sk_buff **pskb, struct rtl8169_private *tp, int pkt_size, dma_addr_t addr) { struct sk_buff *skb; - bool done = false; if (pkt_size >= rx_copybreak) - goto out; + return false; - skb = netdev_alloc_skb_ip_align(tp->dev, pkt_size); + skb = alloc_skb_order0(pkt_size); if (!skb) - goto out; + return false; pci_dma_sync_single_for_cpu(tp->pci_dev, addr, pkt_size, PCI_DMA_FROMDEVICE); - skb_copy_from_linear_data(*sk_buff, skb->data, pkt_size); - *sk_buff = skb; - done = true; -out: - return done; + skb_store_bits(skb, 0, (*pskb)->data, pkt_size); + *pskb = skb; + return true; } /* @@ -4559,10 +4556,10 @@ static int rtl8169_rx_interrupt(struct net_device *dev, pci_unmap_single(pdev, addr, tp->rx_buf_sz, PCI_DMA_FROMDEVICE); tp->Rx_skbuff[entry] = NULL; + skb_put(skb, pkt_size); } rtl8169_rx_csum(skb, status); - skb_put(skb, pkt_size); skb->protocol = eth_type_trans(skb, dev); if (rtl8169_rx_vlan_skb(tp, desc, skb, polling) < 0) { diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 0b53c43..2cc161a 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1841,6 +1841,7 @@ extern int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len); extern int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len); +extern struct sk_buff *alloc_skb_order0(int pkt_size); extern __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to, int len, __wsum csum); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 752c197..4a6195d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1664,6 +1664,53 @@ fault: } EXPORT_SYMBOL(skb_store_bits); +/** + * alloc_skb_order0 - allocate skb with order-0 requirements + * @pkt_size: packet size + * + * Allocate an skb with a head small enough that skb->data should not + * require high order page allocation, and complete with fragments if + * pkt_size is too big. Might be use in drivers RX path : We reserve + * NET_SKB_PAD + NET_IP_ALIGN bytes and use GFP_ATOMIC allocations. + * We also set skb->len to pkt_size, so driver should not call skb_put() + */ +struct sk_buff *alloc_skb_order0(int pkt_size) +{ + int head = min_t(int, pkt_size, SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN)); + struct sk_buff *skb; + + skb = alloc_skb(head + NET_SKB_PAD + NET_IP_ALIGN, + GFP_ATOMIC | __GFP_NOWARN); + if (!skb) + return NULL; + skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN); + skb_put(skb, head); + pkt_size -= head; + + skb->len += pkt_size; + skb->data_len += pkt_size; + skb->truesize += pkt_size; + while (pkt_size) { + int i = skb_shinfo(skb)->nr_frags++; + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + int fragsize = min_t(int, pkt_size, PAGE_SIZE); + struct page *page = alloc_page(GFP_NOWAIT | __GFP_NOWARN); + + if (!page) + goto error; + frag->page = page; + frag->size = fragsize; + frag->page_offset = 0; + pkt_size -= fragsize; + } + return skb; + +error: + kfree_skb(skb); + return NULL; +} +EXPORT_SYMBOL(alloc_skb_order0); + /* Checksum skb data. */ __wsum skb_checksum(const struct sk_buff *skb, int offset, -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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