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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 <davem@davemloft.net>

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jarek Poplawski 2009-02-01 00:41:42 -08:00 committed by David S. Miller
parent 31f4574774
commit 4fb6699481
1 changed files with 35 additions and 10 deletions
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45
net/core/skbuff.c
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@ -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)
static inline struct page *linear_to_page(struct page *page, unsigned int *len,
unsigned int *offset,
struct sk_buff *skb)
{
struct page *p = alloc_pages(GFP_KERNEL, 0);
struct sock *sk = skb->sk;
struct page *p = sk->sk_sndmsg_page;
unsigned int off;
if (!p)
return NULL;
memcpy(page_address(p) + offset, page_address(page) + offset, len);
if (!p) {
new_page:
p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
if (!p)
return NULL;
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);