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Message-Id: <1418216999-17012-4-git-send-email-ogerlitz@mellanox.com>
Date: Wed, 10 Dec 2014 15:09:52 +0200
From: Or Gerlitz <ogerlitz@...lanox.com>
To: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org, Matan Barak <matanb@...lanox.com>,
Amir Vadai <amirv@...lanox.com>, Tal Alon <talal@...lanox.com>,
Jack Morgenstein <jackm@....mellanox.co.il>,
Or Gerlitz <ogerlitz@...lanox.com>
Subject: [PATCH V1 net-next 03/10] net/mlx4_core: Use tasklet for user-space CQ completion events
From: Matan Barak <matanb@...lanox.com>
Previously, we've fired all our completion callbacks straight from our ISR.
Some of those callbacks were lightweight (for example, mlx4_en's and
IPoIB napi callbacks), but some of them did more work (for example,
the user-space RDMA stack uverbs' completion handler). Besides that,
doing more than the minimal work in ISR is generally considered wrong,
it could even lead to a hard lockup of the system. Since when a lot
of completion events are generated by the hardware, the loop over those
events could be so long, that we'll get into a hard lockup by the system
watchdog.
In order to avoid that, add a new way of invoking completion events
callbacks. In the interrupt itself, we add the CQs which receive completion
event to a per-EQ list and schedule a tasklet. In the tasklet context
we loop over all the CQs in the list and invoke the user callback.
Signed-off-by: Matan Barak <matanb@...lanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
---
drivers/infiniband/hw/mlx4/cq.c | 5 ++-
drivers/net/ethernet/mellanox/mlx4/cq.c | 49 +++++++++++++++++++++++++++++
drivers/net/ethernet/mellanox/mlx4/eq.c | 16 +++++++++-
drivers/net/ethernet/mellanox/mlx4/mlx4.h | 12 +++++++
include/linux/mlx4/device.h | 5 +++
5 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/hw/mlx4/cq.c b/drivers/infiniband/hw/mlx4/cq.c
index 1066eec..a3b70f6 100644
--- a/drivers/infiniband/hw/mlx4/cq.c
+++ b/drivers/infiniband/hw/mlx4/cq.c
@@ -233,7 +233,10 @@ struct ib_cq *mlx4_ib_create_cq(struct ib_device *ibdev, int entries, int vector
if (err)
goto err_dbmap;
- cq->mcq.comp = mlx4_ib_cq_comp;
+ if (context)
+ cq->mcq.tasklet_ctx.comp = mlx4_ib_cq_comp;
+ else
+ cq->mcq.comp = mlx4_ib_cq_comp;
cq->mcq.event = mlx4_ib_cq_event;
if (context)
diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c
index 56022d6..060ea63 100644
--- a/drivers/net/ethernet/mellanox/mlx4/cq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cq.c
@@ -52,6 +52,50 @@
#define MLX4_CQ_STATE_ARMED_SOL ( 6 << 8)
#define MLX4_EQ_STATE_FIRED (10 << 8)
+#define TASKLET_THRESHOLD 1000
+
+void mlx4_cq_tasklet_cb(unsigned long data)
+{
+ unsigned long flags;
+ unsigned int i = 0;
+ struct mlx4_eq_tasklet *ctx = (struct mlx4_eq_tasklet *)data;
+ struct mlx4_cq *mcq, *temp;
+
+ spin_lock_irqsave(&ctx->lock, flags);
+ list_splice_tail_init(&ctx->list, &ctx->process_list);
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ list_for_each_entry_safe(mcq, temp, &ctx->process_list, tasklet_ctx.list) {
+ list_del_init(&mcq->tasklet_ctx.list);
+ mcq->tasklet_ctx.comp(mcq);
+ if (atomic_dec_and_test(&mcq->refcount))
+ complete(&mcq->free);
+ if (++i == TASKLET_THRESHOLD)
+ break;
+ }
+
+ if (i == TASKLET_THRESHOLD)
+ tasklet_schedule(&ctx->task);
+}
+
+static void mlx4_add_cq_to_tasklet(struct mlx4_cq *cq)
+{
+ unsigned long flags;
+ struct mlx4_eq_tasklet *tasklet_ctx = cq->tasklet_ctx.priv;
+
+ spin_lock_irqsave(&tasklet_ctx->lock, flags);
+ /* When migrating CQs between EQs will be implemented, please note
+ * that you need to sync this point. It is possible that
+ * while migrating a CQ, completions on the old EQs could
+ * still arrive.
+ */
+ if (list_empty_careful(&cq->tasklet_ctx.list)) {
+ atomic_inc(&cq->refcount);
+ list_add_tail(&cq->tasklet_ctx.list, &tasklet_ctx->list);
+ }
+ spin_unlock_irqrestore(&tasklet_ctx->lock, flags);
+}
+
void mlx4_cq_completion(struct mlx4_dev *dev, u32 cqn)
{
struct mlx4_cq *cq;
@@ -292,6 +336,11 @@ int mlx4_cq_alloc(struct mlx4_dev *dev, int nent,
cq->uar = uar;
atomic_set(&cq->refcount, 1);
init_completion(&cq->free);
+ cq->comp = mlx4_add_cq_to_tasklet;
+ cq->tasklet_ctx.priv =
+ &priv->eq_table.eq[cq->vector].tasklet_ctx;
+ INIT_LIST_HEAD(&cq->tasklet_ctx.list);
+
cq->irq = priv->eq_table.eq[cq->vector].irq;
return 0;
diff --git a/drivers/net/ethernet/mellanox/mlx4/eq.c b/drivers/net/ethernet/mellanox/mlx4/eq.c
index d68b264..3d275fb 100644
--- a/drivers/net/ethernet/mellanox/mlx4/eq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/eq.c
@@ -450,7 +450,7 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
{
struct mlx4_priv *priv = mlx4_priv(dev);
struct mlx4_eqe *eqe;
- int cqn;
+ int cqn = -1;
int eqes_found = 0;
int set_ci = 0;
int port;
@@ -758,6 +758,13 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
eq_set_ci(eq, 1);
+ /* cqn is 24bit wide but is initialized such that its higher bits
+ * are ones too. Thus, if we got any event, cqn's high bits should be off
+ * and we need to schedule the tasklet.
+ */
+ if (!(cqn & ~0xffffff))
+ tasklet_schedule(&eq->tasklet_ctx.task);
+
return eqes_found;
}
@@ -971,6 +978,12 @@ static int mlx4_create_eq(struct mlx4_dev *dev, int nent,
eq->cons_index = 0;
+ INIT_LIST_HEAD(&eq->tasklet_ctx.list);
+ INIT_LIST_HEAD(&eq->tasklet_ctx.process_list);
+ spin_lock_init(&eq->tasklet_ctx.lock);
+ tasklet_init(&eq->tasklet_ctx.task, mlx4_cq_tasklet_cb,
+ (unsigned long)&eq->tasklet_ctx);
+
return err;
err_out_free_mtt:
@@ -1027,6 +1040,7 @@ static void mlx4_free_eq(struct mlx4_dev *dev,
}
}
synchronize_irq(eq->irq);
+ tasklet_disable(&eq->tasklet_ctx.task);
mlx4_mtt_cleanup(dev, &eq->mtt);
for (i = 0; i < npages; ++i)
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
index f48e7c3..b67ef48 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
@@ -43,6 +43,8 @@
#include <linux/timer.h>
#include <linux/semaphore.h>
#include <linux/workqueue.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
#include <linux/mlx4/device.h>
#include <linux/mlx4/driver.h>
@@ -373,6 +375,14 @@ struct mlx4_srq_context {
__be64 db_rec_addr;
};
+struct mlx4_eq_tasklet {
+ struct list_head list;
+ struct list_head process_list;
+ struct tasklet_struct task;
+ /* lock on completion tasklet list */
+ spinlock_t lock;
+};
+
struct mlx4_eq {
struct mlx4_dev *dev;
void __iomem *doorbell;
@@ -383,6 +393,7 @@ struct mlx4_eq {
int nent;
struct mlx4_buf_list *page_list;
struct mlx4_mtt mtt;
+ struct mlx4_eq_tasklet tasklet_ctx;
};
struct mlx4_slave_eqe {
@@ -1146,6 +1157,7 @@ void mlx4_cmd_use_polling(struct mlx4_dev *dev);
int mlx4_comm_cmd(struct mlx4_dev *dev, u8 cmd, u16 param,
unsigned long timeout);
+void mlx4_cq_tasklet_cb(unsigned long data);
void mlx4_cq_completion(struct mlx4_dev *dev, u32 cqn);
void mlx4_cq_event(struct mlx4_dev *dev, u32 cqn, int event_type);
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index cf09e65..3951b53 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -621,6 +621,11 @@ struct mlx4_cq {
atomic_t refcount;
struct completion free;
+ struct {
+ struct list_head list;
+ void (*comp)(struct mlx4_cq *);
+ void *priv;
+ } tasklet_ctx;
};
struct mlx4_qp {
--
1.7.1
--
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