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Update blk-loop patch to latest upstream proposal

This commit is contained in:
Justin M. Forbes 2015-05-06 09:07:35 -05:00
parent fa801da62f
commit 8211a26005
1 changed files with 139 additions and 74 deletions
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213
blk-loop-avoid-too-many-pending-per-work-IO.patch
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@ -1,10 +1,133 @@
Documentation/workqueue.txt:
If there is dependency among multiple work items used
during memory reclaim, they should be queued to separate
wq each with WQ_MEM_RECLAIM.
Loop devices can be stacked, so we have to convert to per-device
workqueue. One example is Fedora live CD.
Fixes: b5dd2f6047ca108001328aac0e8588edd15f1778
Cc: stable@vger.kernel.org (v4.0)
Cc: Justin M. Forbes <jforbes@fedoraproject.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
drivers/block/loop.c | 30 ++++++++++++++----------------
drivers/block/loop.h | 1 +
2 files changed, 15 insertions(+), 16 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ae3fcb4..3dc1598 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -86,8 +86,6 @@ static DEFINE_MUTEX(loop_index_mutex);
static int max_part;
static int part_shift;
-static struct workqueue_struct *loop_wq;
-
/*
* Transfer functions
*/
@@ -725,6 +723,12 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
size = get_loop_size(lo, file);
if ((loff_t)(sector_t)size != size)
goto out_putf;
+ error = -ENOMEM;
+ lo->wq = alloc_workqueue("kloopd%d",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0,
+ lo->lo_number);
+ if (!lo->wq)
+ goto out_putf;
error = 0;
@@ -872,6 +876,8 @@ static int loop_clr_fd(struct loop_device *lo)
lo->lo_flags = 0;
if (!part_shift)
lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+ destroy_workqueue(lo->wq);
+ lo->wq = NULL;
mutex_unlock(&lo->lo_ctl_mutex);
/*
* Need not hold lo_ctl_mutex to fput backing file.
@@ -1425,9 +1431,13 @@ 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;
blk_mq_start_request(bd->rq);
+ if (lo->lo_state != Lo_bound)
+ return -EIO;
+
if (cmd->rq->cmd_flags & REQ_WRITE) {
struct loop_device *lo = cmd->rq->q->queuedata;
bool need_sched = true;
@@ -1441,9 +1451,9 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
spin_unlock_irq(&lo->lo_lock);
if (need_sched)
- queue_work(loop_wq, &lo->write_work);
+ queue_work(lo->wq, &lo->write_work);
} else {
- queue_work(loop_wq, &cmd->read_work);
+ queue_work(lo->wq, &cmd->read_work);
}
return BLK_MQ_RQ_QUEUE_OK;
@@ -1455,9 +1465,6 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
struct loop_device *lo = cmd->rq->q->queuedata;
int ret = -EIO;
- if (lo->lo_state != Lo_bound)
- goto failed;
-
if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))
goto failed;
@@ -1806,13 +1813,6 @@ static int __init loop_init(void)
goto misc_out;
}
- loop_wq = alloc_workqueue("kloopd",
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);
- if (!loop_wq) {
- err = -ENOMEM;
- goto misc_out;
- }
-
blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
THIS_MODULE, loop_probe, NULL, NULL);
@@ -1850,8 +1850,6 @@ static void __exit loop_exit(void)
blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
unregister_blkdev(LOOP_MAJOR, "loop");
- destroy_workqueue(loop_wq);
-
misc_deregister(&loop_misc);
}
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 301c27f..49564ed 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -54,6 +54,7 @@ struct loop_device {
gfp_t old_gfp_mask;
spinlock_t lo_lock;
+ struct workqueue_struct *wq;
struct list_head write_cmd_head;
struct work_struct write_work;
bool write_started;
--
1.9.1
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 limits the max_active parameter of workqueue as 16.
This patch fixes Fedora 22 live booting performance
regression when it is booted from squashfs over dm
@ -23,82 +146,24 @@ as loop block, and ext3fs.img is inside the squashfs
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>
Cc: 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(-)
drivers/block/loop.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ae3fcb4..5a728c6 100644
index 3dc1598..1bee523 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 16, 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) >= 16)
+ 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 {
+ atomic_inc(&lo->pending_per_work_io);
+ cmd->per_work_io = true;
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 301c27f..eb855f5 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;
};
@@ -725,7 +725,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
goto out_putf;
error = -ENOMEM;
lo->wq = alloc_workqueue("kloopd%d",
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0,
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16,
lo->lo_number);
if (!lo->wq)
goto out_putf;
--
1.9.1