From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: [PATCH 3/7] dm: add reserved_bio_based_ios module parameter Date: Thu, 12 Sep 2013 18:24:54 -0400 Message-ID: <1379024698-10487-4-git-send-email-snitzer@redhat.com> References: <1379024698-10487-1-git-send-email-snitzer@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1379024698-10487-1-git-send-email-snitzer@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Frank Mayhar , Mikulas Patocka Cc: dm-devel@redhat.com List-Id: dm-devel.ids Allow user to change the number of IOs that are reserved by bio-based DM's mempools by writing to this file: /sys/module/dm_mod/parameters/reserved_bio_based_ios The default value is RESERVED_BIO_BASED_IOS (16). Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 40 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 8553d03..b44ae19 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -217,6 +217,17 @@ static struct kmem_cache *_io_cache; static struct kmem_cache *_rq_tio_cache; /* + * Bio-based DM's mempools' reserved IOs set by the user + */ +static unsigned reserved_bio_based_ios; + +/* + * A copy of reserved_bio_based_ios because it can change anytime. + * If values disagree, the user has changed reserved_bio_based_ios. + */ +static unsigned reserved_bio_based_ios_latch; + +/* * Request-based DM's mempools' reserved IOs set by the user */ static unsigned reserved_rq_based_ios; @@ -228,10 +239,26 @@ static unsigned reserved_rq_based_ios; static unsigned reserved_rq_based_ios_latch; /* - * This mutex protects reserved_rq_based_ios_latch. + * This mutex protects reserved_bio_based_ios_latch and reserved_rq_based_ios_latch. */ static DEFINE_MUTEX(dm_mempools_lock); +static void __reserved_bio_based_ios_refresh(void) +{ + BUG_ON(!mutex_is_locked(&dm_mempools_lock)); + + reserved_bio_based_ios_latch = ACCESS_ONCE(reserved_bio_based_ios); + + /* + * If the user uses "0", it means default. Modify + * reserved_bio_based_ios to report the default to the user. + */ + if (!reserved_bio_based_ios_latch) { + (void)cmpxchg(&reserved_bio_based_ios, 0, RESERVED_BIO_BASED_IOS); + reserved_bio_based_ios_latch = reserved_bio_based_ios; + } +} + static void __reserved_request_based_ios_refresh(void) { BUG_ON(!mutex_is_locked(&dm_mempools_lock)); @@ -274,6 +301,7 @@ static int __init local_init(void) _major = r; mutex_lock(&dm_mempools_lock); + __reserved_bio_based_ios_refresh(); __reserved_request_based_ios_refresh(); mutex_unlock(&dm_mempools_lock); @@ -2899,7 +2927,14 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u if (type == DM_TYPE_BIO_BASED) { cachep = _io_cache; - pool_size = RESERVED_BIO_BASED_IOS; + + mutex_lock(&dm_mempools_lock); + /* Check if reserved_bio_based_ios changed. */ + if (reserved_bio_based_ios != reserved_bio_based_ios_latch) + __reserved_bio_based_ios_refresh(); + pool_size = reserved_bio_based_ios_latch; + mutex_unlock(&dm_mempools_lock); + front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone); } else if (type == DM_TYPE_REQUEST_BASED) { cachep = _rq_tio_cache; @@ -2969,6 +3004,9 @@ module_exit(dm_exit); module_param(major, uint, 0); MODULE_PARM_DESC(major, "The major number of the device mapper"); +module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools"); + module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools"); -- 1.8.1.4