diff options
Diffstat (limited to 'blk-loop-avoid-too-many-pending-work-IO.patch')
| -rw-r--r-- | blk-loop-avoid-too-many-pending-work-IO.patch | 106 |
1 files changed, 0 insertions, 106 deletions
diff --git a/blk-loop-avoid-too-many-pending-work-IO.patch b/blk-loop-avoid-too-many-pending-work-IO.patch deleted file mode 100644 index 568fc6b9c..000000000 --- a/blk-loop-avoid-too-many-pending-work-IO.patch +++ /dev/null @@ -1,106 +0,0 @@ -From: Ming Lei <ming.lei@canonical.com> -Date: Tue, 28 Apr 2015 14:40:49 -0400 -Subject: [PATCH] blk: loop: avoid too many pending work IO - -If there are too many pending per work I/O, too many -high priority work thread can be generated so that -system performance can be effected. - -This patch limits the max pending per work I/O as 16, -and will fackback to single queue mode when the max -number is reached. - -This patch fixes Fedora 22 live booting performance -regression when it is booted from squashfs over dm -based on loop, and looks the following reasons are -related with the problem: - -- not like other filesyststems(such as ext4), squashfs -is a bit special, and I observed that increasing I/O jobs -to access file in squashfs only improve I/O performance a -little, but it can make big difference for ext4 - -- nested loop: both squashfs.img and ext3fs.img are mounted -as loop block, and ext3fs.img is inside the squashfs - -- during booting, lots of tasks may run concurrently - -Fixes: b5dd2f6047ca108001328aac0e8588edd15f1778 -Cc: stable@vger.kernel.org (v4.0) -Reported-by: Justin M. Forbes <jforbes@fedoraproject.org> -Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> -Signed-off-by: Ming Lei <ming.lei@canonical.com> ---- - drivers/block/loop.c | 19 +++++++++++++++++-- - drivers/block/loop.h | 2 ++ - 2 files changed, 19 insertions(+), 2 deletions(-) - -diff --git a/drivers/block/loop.c b/drivers/block/loop.c -index d7173cb1ea76..4db0301420b0 100644 ---- a/drivers/block/loop.c -+++ b/drivers/block/loop.c -@@ -1425,13 +1425,24 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, - const struct blk_mq_queue_data *bd) - { - struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); -+ struct loop_device *lo = cmd->rq->q->queuedata; -+ bool single_queue = !!(cmd->rq->cmd_flags & REQ_WRITE); -+ -+ /* -+ * Fallback to single queue mode if the pending per work -+ * I/O number reaches 32, otherwise too many high priority -+ * worker thread may effect system performance as reported -+ * in fedora live booting from squashfs over loop. -+ */ -+ if (atomic_read(&lo->pending_per_work_io) >= 32) -+ single_queue = true; - - blk_mq_start_request(bd->rq); - -- if (cmd->rq->cmd_flags & REQ_WRITE) { -- struct loop_device *lo = cmd->rq->q->queuedata; -+ if (single_queue) { - bool need_sched = true; - -+ cmd->per_work_io = false; - spin_lock_irq(&lo->lo_lock); - if (lo->write_started) - need_sched = false; -@@ -1443,6 +1454,8 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, - if (need_sched) - queue_work(loop_wq, &lo->write_work); - } else { -+ cmd->per_work_io = true; -+ atomic_inc(&lo->pending_per_work_io); - queue_work(loop_wq, &cmd->read_work); - } - -@@ -1467,6 +1480,8 @@ static void loop_handle_cmd(struct loop_cmd *cmd) - if (ret) - cmd->rq->errors = -EIO; - blk_mq_complete_request(cmd->rq); -+ if (cmd->per_work_io) -+ atomic_dec(&lo->pending_per_work_io); - } - - static void loop_queue_write_work(struct work_struct *work) -diff --git a/drivers/block/loop.h b/drivers/block/loop.h -index 301c27f8323f..eb855f57a62d 100644 ---- a/drivers/block/loop.h -+++ b/drivers/block/loop.h -@@ -57,6 +57,7 @@ struct loop_device { - struct list_head write_cmd_head; - struct work_struct write_work; - bool write_started; -+ atomic_t pending_per_work_io; - int lo_state; - struct mutex lo_ctl_mutex; - -@@ -68,6 +69,7 @@ struct loop_device { - struct loop_cmd { - struct work_struct read_work; - struct request *rq; -+ bool per_work_io; - struct list_head list; - }; - |