Re: [PATCH 12/13] ll_rw_blk: temporarily enable max_segments tweaking

Andrew Morton
2007-05-10T10:50:44Z

On Thu, 10 May 2007 12:21:54 +0200 Jens Axboe <jens.axboe@oracle.com> wrote:

> Expose this setting for now, so that users can play with enabling
> large commands without defaulting it to on globally.
>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> ---
> block/ll_rw_blk.c | 22 ++++++++++++++++++++++
> 1 files changed, 22 insertions(+), 0 deletions(-)
>
> diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
> index b01a5f2..cf05396 100644
> --- a/block/ll_rw_blk.c
> +++ b/block/ll_rw_blk.c
> @@ -3930,7 +3930,22 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
> return queue_var_show(max_hw_sectors_kb, (page));
> }
>
> +static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
> +{
> + return queue_var_show(q->max_phys_segments, page);
> +}
> +
> +static ssize_t queue_max_segments_store(struct request_queue *q, const char *page, size_t count)

100-col xterm?

> +{
> + unsigned long segments;
> + ssize_t ret = queue_var_store(&segments, page, count);
>
> + spin_lock_irq(q->queue_lock);
> + q->max_phys_segments = segments;
> + spin_unlock_irq(q->queue_lock);

Fishy locking?

> + return ret;
> +}
> static struct queue_sysfs_entry queue_requests_entry = {
> .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
> .show = queue_requests_show,
> @@ -3954,6 +3969,12 @@ static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
> .show = queue_max_hw_sectors_show,
> };
>
> +static struct queue_sysfs_entry queue_max_segments_entry = {
> + .attr = {.name = "max_segments", .mode = S_IRUGO |S_IWUSR },

whitespace went funny.

> + .show = queue_max_segments_show,
> + .store = queue_max_segments_store,
> +};
> +
> static struct queue_sysfs_entry queue_iosched_entry = {
> .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
> .show = elv_iosched_show,
> @@ -3965,6 +3986,7 @@ static struct attribute *default_attrs[] = {
> &queue_ra_entry.attr,
> &queue_max_hw_sectors_entry.attr,
> &queue_max_sectors_entry.attr,
> + &queue_max_segments_entry.attr,
> &queue_iosched_entry.attr,
> NULL,
> };