From: Wu Fengguang backing_dev_info.ra_pages0 is a user configurable parameter that controls the readahead size on start-of-file. Signed-off-by: Wu Fengguang Signed-off-by: Andrew Morton --- block/ll_rw_blk.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff -puN block/ll_rw_blk.c~readahead-initial-method-user-recommended-size block/ll_rw_blk.c --- devel/block/ll_rw_blk.c~readahead-initial-method-user-recommended-size 2006-05-27 23:06:36.000000000 -0700 +++ devel-akpm/block/ll_rw_blk.c 2006-05-27 23:06:36.000000000 -0700 @@ -3764,6 +3764,29 @@ queue_ra_store(struct request_queue *q, return ret; } +static ssize_t queue_initial_ra_show(struct request_queue *q, char *page) +{ + int kb = q->backing_dev_info.ra_pages0 << (PAGE_CACHE_SHIFT - 10); + + return queue_var_show(kb, (page)); +} + +static ssize_t +queue_initial_ra_store(struct request_queue *q, const char *page, size_t count) +{ + unsigned long kb, ra; + ssize_t ret = queue_var_store(&kb, page, count); + + ra = kb >> (PAGE_CACHE_SHIFT - 10); + q->backing_dev_info.ra_pages0 = ra; + + ra = kb * 1024; + if (q->backing_dev_info.ra_expect_bytes > ra) + q->backing_dev_info.ra_expect_bytes = ra; + + return ret; +} + static ssize_t queue_max_sectors_show(struct request_queue *q, char *page) { int max_sectors_kb = q->max_sectors >> 1; @@ -3821,6 +3844,12 @@ static struct queue_sysfs_entry queue_ra .store = queue_ra_store, }; +static struct queue_sysfs_entry queue_initial_ra_entry = { + .attr = {.name = "initial_ra_kb", .mode = S_IRUGO | S_IWUSR }, + .show = queue_initial_ra_show, + .store = queue_initial_ra_store, +}; + static struct queue_sysfs_entry queue_max_sectors_entry = { .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR }, .show = queue_max_sectors_show, @@ -3841,6 +3870,7 @@ static struct queue_sysfs_entry queue_io static struct attribute *default_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, + &queue_initial_ra_entry.attr, &queue_max_hw_sectors_entry.attr, &queue_max_sectors_entry.attr, &queue_iosched_entry.attr, _