| Message ID | 200908101618.21060.knikanth@suse.de (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
Hi Nikanth, On 08/10/2009 07:48 PM +0900, Nikanth Karthikesan wrote: > Intialize the request_queue and elevator only when the device is marked as > a request-based device. This avoids unnecessary creation of mempool for > requests. Also we wrongly initialize the elevator even for bio-based devices. > As the /sys/block/dm-*/queue/scheduler is exported for device-mapper devices, > it is possible to confuse with scheduler options for bio-based devices where > scheduler is not at all used. Thank you for working on this. Actually, I had tried this delayed allocation thing before, but I chose the current implementation since I couldn't solve some problems, which your patch also has. Please see my comment below. > @@ -2203,6 +2199,25 @@ int dm_swap_table(struct mapped_device *md, struct dm_table *table) > goto out; > } > > + /* new device is being marked as request-based */ > + if (!md->map && dm_table_request_based(table)) { > + /* initialize queue for request-based dm */ > + r = blk_init_allocated_queue(md->queue, dm_request_fn, NULL); > + if (r) > + goto out; Generally, dm must not allocate memory during resume because it may cause a deadlock in no memory situation. However, there is no I/O on this device at this point, so the allocation should be ok for this special case. I think some comments are needed here to describe that. > + > + /* > + * reinitialize make_request_fn as it was reset to the > + * default __make_request by blk_init_allocate_queue > + */ > + md->saved_make_request_fn = md->queue->make_request_fn; > + blk_queue_make_request(md->queue, dm_request); > + > + blk_queue_softirq_done(md->queue, dm_softirq_done); > + blk_queue_prep_rq(md->queue, dm_prep_fn); > + blk_queue_lld_busy(md->queue, dm_lld_busy); > + } > + > __unbind(md); > r = __bind(md, table, &limits); The queue has been registered at the device creation time by add_disk() in alloc_dev(). Since the queue is reconfigured (elevator is attached), you have to update the queue registration (e.g. unregister, then re-register). But it may not be easy. At least, there is no exported interface to unregister/re-register queue. Thanks, Kiyoshi Ueda -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 8a311ea..8e5a2fd 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1749,22 +1749,21 @@ static struct mapped_device *alloc_dev(int minor) INIT_LIST_HEAD(&md->uevent_list); spin_lock_init(&md->uevent_lock); - md->queue = blk_init_queue(dm_request_fn, NULL); + md->queue = blk_alloc_queue(GFP_KERNEL); if (!md->queue) goto bad_queue; /* * Request-based dm devices cannot be stacked on top of bio-based dm - * devices. The type of this dm device has not been decided yet, - * although we initialized the queue using blk_init_queue(). + * devices. The type of this dm device has not been decided yet. * The type is decided at the first table loading time. * To prevent problematic device stacking, clear the queue flag * for request stacking support until then. * * This queue is new, so no concurrency on the queue_flags. */ + md->queue->queue_flags = QUEUE_FLAG_DEFAULT; queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue); - md->saved_make_request_fn = md->queue->make_request_fn; md->queue->queuedata = md; md->queue->backing_dev_info.congested_fn = dm_any_congested; md->queue->backing_dev_info.congested_data = md; @@ -1772,9 +1771,6 @@ static struct mapped_device *alloc_dev(int minor) blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); md->queue->unplug_fn = dm_unplug_all; blk_queue_merge_bvec(md->queue, dm_merge_bvec); - blk_queue_softirq_done(md->queue, dm_softirq_done); - blk_queue_prep_rq(md->queue, dm_prep_fn); - blk_queue_lld_busy(md->queue, dm_lld_busy); md->disk = alloc_disk(1); if (!md->disk) @@ -2203,6 +2199,25 @@ int dm_swap_table(struct mapped_device *md, struct dm_table *table) goto out; } + /* new device is being marked as request-based */ + if (!md->map && dm_table_request_based(table)) { + /* initialize queue for request-based dm */ + r = blk_init_allocated_queue(md->queue, dm_request_fn, NULL); + if (r) + goto out; + + /* + * reinitialize make_request_fn as it was reset to the + * default __make_request by blk_init_allocate_queue + */ + md->saved_make_request_fn = md->queue->make_request_fn; + blk_queue_make_request(md->queue, dm_request); + + blk_queue_softirq_done(md->queue, dm_softirq_done); + blk_queue_prep_rq(md->queue, dm_prep_fn); + blk_queue_lld_busy(md->queue, dm_lld_busy); + } + __unbind(md); r = __bind(md, table, &limits);
Intialize the request_queue and elevator only when the device is marked as a request-based device. This avoids unnecessary creation of mempool for requests. Also we wrongly initialize the elevator even for bio-based devices. As the /sys/block/dm-*/queue/scheduler is exported for device-mapper devices, it is possible to confuse with scheduler options for bio-based devices where scheduler is not at all used. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> --- -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel