From 4fb669948116d928ae44262ab7743732c574630d Mon Sep 17 00:00:00 2001 From: Jarek Poplawski Date: Sun, 1 Feb 2009 00:41:42 -0800 Subject: net: Optimize memory usage when splicing from sockets. The recent fix of data corruption when splicing from sockets uses memory very inefficiently allocating a new page to copy each chunk of linear part of skb. This patch uses the same page until it's full (almost) by caching the page in sk_sndmsg_page field. With changes from David S. Miller Signed-off-by: Jarek Poplawski Signed-off-by: David S. Miller --- net/core/skbuff.c | 47 ++++++++++++++++++++++++++++++++++++----------- 1 file changed, 36 insertions(+), 11 deletions(-) (limited to 'net') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f20e758fe46..e55d1ef5690 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1333,14 +1333,39 @@ static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i) put_page(spd->pages[i]); } -static inline struct page *linear_to_page(struct page *page, unsigned int len, - unsigned int offset) -{ - struct page *p = alloc_pages(GFP_KERNEL, 0); +static inline struct page *linear_to_page(struct page *page, unsigned int *len, + unsigned int *offset, + struct sk_buff *skb) +{ + struct sock *sk = skb->sk; + struct page *p = sk->sk_sndmsg_page; + unsigned int off; + + if (!p) { +new_page: + p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0); + if (!p) + return NULL; - if (!p) - return NULL; - memcpy(page_address(p) + offset, page_address(page) + offset, len); + off = sk->sk_sndmsg_off = 0; + /* hold one ref to this page until it's full */ + } else { + unsigned int mlen; + + off = sk->sk_sndmsg_off; + mlen = PAGE_SIZE - off; + if (mlen < 64 && mlen < *len) { + put_page(p); + goto new_page; + } + + *len = min_t(unsigned int, *len, mlen); + } + + memcpy(page_address(p) + off, page_address(page) + *offset, *len); + sk->sk_sndmsg_off += *len; + *offset = off; + get_page(p); return p; } @@ -1349,21 +1374,21 @@ static inline struct page *linear_to_page(struct page *page, unsigned int len, * Fill page/offset/length into spd, if it can hold more pages. */ static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page, - unsigned int len, unsigned int offset, + unsigned int *len, unsigned int offset, struct sk_buff *skb, int linear) { if (unlikely(spd->nr_pages == PIPE_BUFFERS)) return 1; if (linear) { - page = linear_to_page(page, len, offset); + page = linear_to_page(page, len, &offset, skb); if (!page) return 1; } else get_page(page); spd->pages[spd->nr_pages] = page; - spd->partial[spd->nr_pages].len = len; + spd->partial[spd->nr_pages].len = *len; spd->partial[spd->nr_pages].offset = offset; spd->nr_pages++; @@ -1405,7 +1430,7 @@ static inline int __splice_segment(struct page *page, unsigned int poff, /* the linear region may spread across several pages */ flen = min_t(unsigned int, flen, PAGE_SIZE - poff); - if (spd_fill_page(spd, page, flen, poff, skb, linear)) + if (spd_fill_page(spd, page, &flen, poff, skb, linear)) return 1; __segment_seek(&page, &poff, &plen, flen); -- cgit v1.2.3