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[PATCH] splice: speedup __generic_file_splice_read 

Using find_get_page() is a lot faster than find_or_create_page(). This
gets splice a lot closer to sendfile() for fd -> socket transfers.

Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe 2006-04-11 13:52:47 +02:00
parent b92ce55893
commit 7480a90435
1 changed files with 63 additions and 11 deletions
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74
fs/splice.c
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@ -240,7 +240,7 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
struct page *pages[PIPE_BUFFERS];
struct page *page;
pgoff_t index;
int i;
int i, error;
index = in->f_pos >> PAGE_CACHE_SHIFT;
offset = in->f_pos & ~PAGE_CACHE_MASK;
@ -260,32 +260,84 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
/*
* now fill in the holes
*/
error = 0;
for (i = 0; i < nr_pages; i++, index++) {
find_page:
/*
* no page there, look one up / create it
* lookup the page for this index
*/
page = find_or_create_page(mapping, index,
mapping_gfp_mask(mapping));
if (!page)
break;
page = find_get_page(mapping, index);
if (!page) {
/*
* If in nonblock mode then dont block on
* readpage (we've kicked readahead so there
* will be asynchronous progress):
*/
if (flags & SPLICE_F_NONBLOCK)
break;
if (PageUptodate(page))
unlock_page(page);
else {
int error = mapping->a_ops->readpage(in, page);
/*
* page didn't exist, allocate one
*/
page = page_cache_alloc_cold(mapping);
if (!page)
break;
error = add_to_page_cache_lru(page, mapping, index,
mapping_gfp_mask(mapping));
if (unlikely(error)) {
page_cache_release(page);
break;
}
goto readpage;
}
/*
* If the page isn't uptodate, we may need to start io on it
*/
if (!PageUptodate(page)) {
lock_page(page);
/*
* page was truncated, stop here. if this isn't the
* first page, we'll just complete what we already
* added
*/
if (!page->mapping) {
unlock_page(page);
page_cache_release(page);
break;
}
/*
* page was already under io and is now done, great
*/
if (PageUptodate(page)) {
unlock_page(page);
goto fill_it;
}
readpage:
/*
* need to read in the page
*/
error = mapping->a_ops->readpage(in, page);
if (unlikely(error)) {
page_cache_release(page);
if (error == AOP_TRUNCATED_PAGE)
goto find_page;
break;
}
}
fill_it:
pages[i] = page;
}
if (i)
return move_to_pipe(pipe, pages, i, offset, len, flags);
return 0;
return error;
}
/**