From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: [PATCH 7/7] dm: optimize clone_rq() when track_peak_rq_based_ios is disabled Date: Thu, 12 Sep 2013 18:24:58 -0400 Message-ID: <1379024698-10487-8-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 Make use of static keys to eliminate the relevant branch in clone_rq() when dm_mod's 'track_peak_rq_based_ios' paramter is set to 0 (disabled). Even if 'track_peak_rq_based_ios' is set to 0 it will not take effect until the next request-based table reload. Once it is disabled the 'peak_rq_based_ios' parameter will be reset to 0. Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index de83930..d9e38a7 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -19,6 +19,7 @@ #include #include #include +#include #include @@ -242,10 +243,14 @@ static unsigned reserved_rq_based_ios_latch; * Optionally track the maximum numbers of IOs in a cloned request. */ static unsigned track_peak_rq_based_ios; +static unsigned track_peak_rq_based_ios_latch; static unsigned peak_rq_based_ios; +static struct static_key_deferred track_peak_rq_based_ios_enabled; /* defaults to false */ + /* - * This mutex protects reserved_bio_based_ios_latch and reserved_rq_based_ios_latch. + * This mutex protects reserved_bio_based_ios_latch, reserved_rq_based_ios_latch + * and track_peak_rq_based_ios_latch. */ static DEFINE_MUTEX(dm_mempools_lock); @@ -305,6 +310,26 @@ unsigned dm_get_reserved_rq_based_ios(void) } EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios); +static void __track_peak_rq_based_ios_refresh(void) +{ + bool enabled = static_key_false(&track_peak_rq_based_ios_enabled.key); + + BUG_ON(!mutex_is_locked(&dm_mempools_lock)); + + track_peak_rq_based_ios_latch = ACCESS_ONCE(track_peak_rq_based_ios); + + if (track_peak_rq_based_ios_latch) { + if (enabled) + return; /* already enabled */ + static_key_slow_inc(&track_peak_rq_based_ios_enabled.key); + } else { + if (!enabled) + return; /* already disabled */ + static_key_slow_dec(&track_peak_rq_based_ios_enabled.key); + ACCESS_ONCE(peak_rq_based_ios) = 0; + } +} + static int __init local_init(void) { int r = -ENOMEM; @@ -1725,7 +1750,7 @@ static struct request *clone_rq(struct request *rq, struct mapped_device *md, return NULL; } - if (unlikely(ACCESS_ONCE(track_peak_rq_based_ios))) { + if (static_key_false(&track_peak_rq_based_ios_enabled.key)) { struct bio *bio; unsigned num_bios = 0; @@ -2984,6 +3009,10 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u if (reserved_rq_based_ios != reserved_rq_based_ios_latch) __reserved_request_based_ios_refresh(); pool_size = reserved_rq_based_ios_latch; + + /* Check if track_peak_rq_based_ios changed. */ + if (track_peak_rq_based_ios != track_peak_rq_based_ios_latch) + __track_peak_rq_based_ios_refresh(); mutex_unlock(&dm_mempools_lock); front_pad = offsetof(struct dm_rq_clone_bio_info, clone); -- 1.8.1.4