From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: [PATCH 6/7] dm: track the maximum number of bios in a cloned request Date: Thu, 12 Sep 2013 18:24:57 -0400 Message-ID: <1379024698-10487-7-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 If /sys/modules/dm_mod/parameters/track_peak_rq_based_ios is set to 1 it enables the tracking of the maximum number of bios in a cloned request. The maximum number of bios in a cloned request is then exposed through the following read-only parameter: /sys/modules/dm_mod/parameters/peak_rq_based_ios This information can be useful when deciding on a value for dm_mod's 'reserved_rq_based_ios' parameter. Otherwise, 'track_peak_rq_based_ios' should be kept disabled (the default). Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 186f77d..de83930 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -239,6 +239,12 @@ static unsigned reserved_rq_based_ios; 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 peak_rq_based_ios; + +/* * This mutex protects reserved_bio_based_ios_latch and reserved_rq_based_ios_latch. */ static DEFINE_MUTEX(dm_mempools_lock); @@ -1719,6 +1725,16 @@ static struct request *clone_rq(struct request *rq, struct mapped_device *md, return NULL; } + if (unlikely(ACCESS_ONCE(track_peak_rq_based_ios))) { + struct bio *bio; + unsigned num_bios = 0; + + __rq_for_each_bio(bio, clone) + num_bios++; + if (num_bios > ACCESS_ONCE(peak_rq_based_ios)) + ACCESS_ONCE(peak_rq_based_ios) = num_bios; + } + return clone; } @@ -3034,6 +3050,12 @@ 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"); +module_param(track_peak_rq_based_ios, uint, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(peak_rq_based_ios, "Enable tracking the maximum IOs in a cloned request"); + +module_param(peak_rq_based_ios, uint, S_IRUGO); +MODULE_PARM_DESC(peak_rq_based_ios, "Tracks the maximum IOs in a cloned request"); + MODULE_DESCRIPTION(DM_NAME " driver"); MODULE_AUTHOR("Joe Thornber "); MODULE_LICENSE("GPL"); -- 1.8.1.4