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Date: Fri, 31 May 2013 19:31:11 -0500
From: "Philip J. Kelleher" <pjk1939@...ux.vnet.ibm.com>
To: axboe@...nel.dk
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 5/8] rsxx: Fixes CPU usage issues on RHEL 6 Kernels.
From: Philip J Kelleher <pjk1939@...ux.vnet.ibm.com>
The RHEL 6.x version of the driver is using the legacy
workqueue create function, 'create_singlethread_workqueue'.
This would cause heavy usage of one CPU if data was being
thrashed pretty hard. So, in order to fix it, workqueues
are now being created with 'create_workqueue' and
synchronization with mutexes.
Signed-off-by: Philip J Kelleher <pjk1939@...ux.vnet.ibm.com>
-------------------------------------------------------------------------------
diff -uprN -X linux-block/Documentation/dontdiff linux-block-vanilla/drivers/block/rsxx/dma.c linux-block/drivers/block/rsxx/dma.c
--- linux-block-vanilla/drivers/block/rsxx/dma.c 2013-05-31 16:33:27.680101047 -0500
+++ linux-block/drivers/block/rsxx/dma.c 2013-05-31 17:01:30.910821876 -0500
@@ -382,15 +382,13 @@ static void dma_engine_stalled(unsigned
}
}
-static void rsxx_issue_dmas(struct work_struct *work)
+static void rsxx_issue_dmas(struct rsxx_dma_ctrl *ctrl)
{
- struct rsxx_dma_ctrl *ctrl;
struct rsxx_dma *dma;
int tag;
int cmds_pending = 0;
struct hw_cmd *hw_cmd_buf;
- ctrl = container_of(work, struct rsxx_dma_ctrl, issue_dma_work);
hw_cmd_buf = ctrl->cmd.buf;
if (unlikely(ctrl->card->halt) ||
@@ -470,9 +468,8 @@ static void rsxx_issue_dmas(struct work_
}
}
-static void rsxx_dma_done(struct work_struct *work)
+static void rsxx_dma_done(struct rsxx_dma_ctrl *ctrl)
{
- struct rsxx_dma_ctrl *ctrl;
struct rsxx_dma *dma;
unsigned long flags;
u16 count;
@@ -480,7 +477,6 @@ static void rsxx_dma_done(struct work_st
u8 tag;
struct hw_status *hw_st_buf;
- ctrl = container_of(work, struct rsxx_dma_ctrl, dma_done_work);
hw_st_buf = ctrl->status.buf;
if (unlikely(ctrl->card->halt) ||
@@ -556,6 +552,28 @@ static void rsxx_dma_done(struct work_st
spin_unlock_bh(&ctrl->queue_lock);
}
+static void rsxx_schedule_issue(struct work_struct *work)
+{
+ struct rsxx_dma_ctrl *ctrl;
+
+ ctrl = container_of(work, struct rsxx_dma_ctrl, issue_dma_work);
+
+ mutex_lock(&ctrl->work_lock);
+ rsxx_issue_dmas(ctrl);
+ mutex_unlock(&ctrl->work_lock);
+}
+
+static void rsxx_schedule_done(struct work_struct *work)
+{
+ struct rsxx_dma_ctrl *ctrl;
+
+ ctrl = container_of(work, struct rsxx_dma_ctrl, dma_done_work);
+
+ mutex_lock(&ctrl->work_lock);
+ rsxx_dma_done(ctrl);
+ mutex_unlock(&ctrl->work_lock);
+}
+
static int rsxx_queue_discard(struct rsxx_cardinfo *card,
struct list_head *q,
unsigned int laddr,
@@ -799,6 +817,7 @@ static int rsxx_dma_ctrl_init(struct pci
spin_lock_init(&ctrl->trackers->lock);
spin_lock_init(&ctrl->queue_lock);
+ mutex_init(&ctrl->work_lock);
INIT_LIST_HEAD(&ctrl->queue);
setup_timer(&ctrl->activity_timer, dma_engine_stalled,
@@ -812,8 +831,8 @@ static int rsxx_dma_ctrl_init(struct pci
if (!ctrl->done_wq)
return -ENOMEM;
- INIT_WORK(&ctrl->issue_dma_work, rsxx_issue_dmas);
- INIT_WORK(&ctrl->dma_done_work, rsxx_dma_done);
+ INIT_WORK(&ctrl->issue_dma_work, rsxx_schedule_issue);
+ INIT_WORK(&ctrl->dma_done_work, rsxx_schedule_done);
st = rsxx_hw_buffers_init(dev, ctrl);
if (st)
diff -uprN -X linux-block/Documentation/dontdiff linux-block-vanilla/drivers/block/rsxx/rsxx_priv.h linux-block/drivers/block/rsxx/rsxx_priv.h
--- linux-block-vanilla/drivers/block/rsxx/rsxx_priv.h 2013-05-31 16:33:27.685040463 -0500
+++ linux-block/drivers/block/rsxx/rsxx_priv.h 2013-05-31 16:46:25.714020362 -0500
@@ -115,6 +115,7 @@ struct rsxx_dma_ctrl {
struct timer_list activity_timer;
struct dma_tracker_list *trackers;
struct rsxx_dma_stats stats;
+ struct mutex work_lock;
};
struct rsxx_cardinfo {
--
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