From: Ram Pai Remove the up-front readahead code fromthe core pagecache read function: it's really bad for large reads. --- mm/filemap.c | 12 ++---------- 1 files changed, 2 insertions(+), 10 deletions(-) diff -puN mm/filemap.c~readahead-partial-backout mm/filemap.c --- 25/mm/filemap.c~readahead-partial-backout 2004-01-09 22:19:32.000000000 -0800 +++ 25-akpm/mm/filemap.c 2004-01-09 22:19:32.000000000 -0800 @@ -587,22 +587,13 @@ void do_generic_mapping_read(struct addr read_actor_t actor) { struct inode *inode = mapping->host; - unsigned long index, offset, last; + unsigned long index, offset; struct page *cached_page; int error; cached_page = NULL; index = *ppos >> PAGE_CACHE_SHIFT; offset = *ppos & ~PAGE_CACHE_MASK; - last = (*ppos + desc->count) >> PAGE_CACHE_SHIFT; - - /* - * Let the readahead logic know upfront about all - * the pages we'll need to satisfy this request - */ - for (; index < last; index++) - page_cache_readahead(mapping, ra, filp, index); - index = *ppos >> PAGE_CACHE_SHIFT; for (;;) { struct page *page; @@ -621,6 +612,7 @@ void do_generic_mapping_read(struct addr } cond_resched(); + page_cache_readahead(mapping, ra, filp, index); nr = nr - offset; find_page: _