On Mon, Jan 05 2009, James Bottomley wrote:
> On Mon, 2009-01-05 at 20:02 +0100, Bartlomiej Zolnierkiewicz wrote:
> > On Monday 05 January 2009, Jens Axboe wrote:
> > > On Mon, Jan 05 2009, Bartlomiej Zolnierkiewicz wrote:
> > > > From: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
> > > > Subject: [PATCH] block: export SSD/non-rotational queue flag through sysfs
> > > >
> > > > For some devices (i.e. CFA ATA) we can't reliably detect whether
> > > > the device is of rotational or non-rotational type so we need to
> > > > leave the final decision about this setting to the user-space.
> > >
> > > I agree with that, was actually planning on doing that myself.
> > >
> > > > @@ -146,8 +167,8 @@ static ssize_t queue_nomerges_store(stru
> > > > queue_flag_set(QUEUE_FLAG_NOMERGES, q);
> > > > else
> > > > queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
> > > > -
> > > > spin_unlock_irq(q->queue_lock);
> > > > +
> > > > return ret;
> > > > }
> > > >
> > >
> > > Hmm?
> >
> > This is just a "bonus". :)
> >
> > > > @@ -210,6 +231,12 @@ static struct queue_sysfs_entry queue_hw
> > > > .show = queue_hw_sector_size_show,
> > > > };
> > > >
> > > > +static struct queue_sysfs_entry queue_nonrot_entry = {
> > > > + .attr = {.name = "nonrot", .mode = S_IRUGO | S_IWUSR },
> > > > + .show = queue_nonrot_show,
> > > > + .store = queue_nonrot_store,
> > > > +};
> > > > +
> > >
> > > Lets please use a better name for export reasons, non-rotational is a
> > > lot better. Nobody will know what nonrot means :-)
> >
> > Yeah...
> >
> > From: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
> > Subject: [PATCH v2] block: export SSD/non-rotational queue flag through sysfs
> >
> > For some devices (i.e. CFA ATA) we can't reliably detect whether
> > the device is of rotational or non-rotational type so we need to
> > leave the final decision about this setting to the user-space.
> >
> > As a bonus do a minor CodingStyle fixup in queue_nomerges_store().
> >
> > Suggested-by: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
> > ---
> > block/blk-sysfs.c | 30 +++++++++++++++++++++++++++++-
> > 1 file changed, 29 insertions(+), 1 deletion(-)
> >
> > Index: b/block/blk-sysfs.c
> > ===================================================================
> > --- a/block/blk-sysfs.c
> > +++ b/block/blk-sysfs.c
> > @@ -130,6 +130,27 @@ static ssize_t queue_max_hw_sectors_show
> > return queue_var_show(max_hw_sectors_kb, (page));
> > }
> >
> > +static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
> > +{
> > + return queue_var_show(blk_queue_nonrot(q), page);
> > +}
> > +
> > +static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
> > + size_t count)
> > +{
> > + unsigned long nm;
> > + ssize_t ret = queue_var_store(&nm, page, count);
> > +
> > + spin_lock_irq(q->queue_lock);
> > + if (nm)
> > + queue_flag_set(QUEUE_FLAG_NONROT, q);
> > + else
> > + queue_flag_clear(QUEUE_FLAG_NONROT, q);
> > + spin_unlock_irq(q->queue_lock);
> > +
> > + return ret;
> > +}
> > +
> > static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
> > {
> > return queue_var_show(blk_queue_nomerges(q), page);
> > @@ -146,8 +167,8 @@ static ssize_t queue_nomerges_store(stru
> > queue_flag_set(QUEUE_FLAG_NOMERGES, q);
> > else
> > queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
> > -
> > spin_unlock_irq(q->queue_lock);
> > +
> > return ret;
> > }
> >
> > @@ -210,6 +231,12 @@ static struct queue_sysfs_entry queue_hw
> > .show = queue_hw_sector_size_show,
> > };
> >
> > +static struct queue_sysfs_entry queue_nonrot_entry = {
> > + .attr = {.name = "non-rotational", .mode = S_IRUGO | S_IWUSR },
> > + .show = queue_nonrot_show,
> > + .store = queue_nonrot_store,
> > +};
> > +
> > static struct queue_sysfs_entry queue_nomerges_entry = {
> > .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
> > .show = queue_nomerges_show,
> > @@ -229,6 +256,7 @@ static struct attribute *default_attrs[]
> > &queue_max_sectors_entry.attr,
> > &queue_iosched_entry.attr,
> > &queue_hw_sector_size_entry.attr,
> > + &queue_nonrot_entry.attr,
> > &queue_nomerges_entry.attr,
> > &queue_rq_affinity_entry.attr,
> > NULL,
>
> Almost all block devices might find this useful. Ought not this flag to
> be in the block layer appearing under /sys/block/<dev>?
The block layer only uses it for scheduling purposes, in which case it
fits well in queue/ since you need the io scheduler.
--
Jens Axboe
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