From: Fengguang Wu Date: Thu, 19 Jul 2007 08:48:05 +0000 (-0700) Subject: readahead: move synchronous readahead call out of splice loop X-Git-Tag: v2.6.23-rc1~429 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=431a4820bfcdf7ff530e745230bafb06c9bf2d6d;p=linux-2.6 readahead: move synchronous readahead call out of splice loop Move synchronous page_cache_readahead_ondemand() call out of splice loop. This avoids one pointless page allocation/insertion in case of non-zero ra_pages, or many pointless readahead calls in case of zero ra_pages. Note that if a user sets ra_pages to less than PIPE_BUFFERS=16 pages, he will not get expected readahead behavior anyway. The splice code works in batches of 16 pages, which can be taken as another form of synchronous readahead. Signed-off-by: Fengguang Wu Cc: Jens Axboe Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/splice.c b/fs/splice.c index 722449f7d5..421b3b8211 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -290,13 +290,17 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, * Lookup the (hopefully) full range of pages we need. */ spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); + index += spd.nr_pages; /* * If find_get_pages_contig() returned fewer pages than we needed, - * allocate the rest and fill in the holes. + * readahead/allocate the rest and fill in the holes. */ + if (spd.nr_pages < nr_pages) + page_cache_readahead_ondemand(mapping, &in->f_ra, in, + NULL, index, nr_pages - spd.nr_pages); + error = 0; - index += spd.nr_pages; while (spd.nr_pages < nr_pages) { /* * Page could be there, find_get_pages_contig() breaks on @@ -304,9 +308,6 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, */ page = find_get_page(mapping, index); if (!page) { - page_cache_readahead_ondemand(mapping, &in->f_ra, in, - NULL, index, nr_pages - spd.nr_pages); - /* * page didn't exist, allocate one. */