IB/qib: Optimize CQ callbacks
The current workqueue implemention has the following performance
deficiencies on QDR HCAs:
- The CQ call backs tend to run on the CPUs processing the
receive queues
- The single thread queue isn't optimal for multiple HCAs
This patch adds a dedicated per HCA bound thread to process CQ callbacks.
Reviewed-by: Ramkrishna Vepa <ramkrishna.vepa@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/qib/qib_cq.c b/drivers/infiniband/hw/qib/qib_cq.c
index 5246aa4..ab4e11c 100644
--- a/drivers/infiniband/hw/qib/qib_cq.c
+++ b/drivers/infiniband/hw/qib/qib_cq.c
@@ -1,4 +1,5 @@
/*
+ * Copyright (c) 2013 Intel Corporation. All rights reserved.
* Copyright (c) 2006, 2007, 2008, 2010 QLogic Corporation. All rights reserved.
* Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
*
@@ -34,8 +35,10 @@
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
+#include <linux/kthread.h>
#include "qib_verbs.h"
+#include "qib.h"
/**
* qib_cq_enter - add a new entry to the completion queue
@@ -102,13 +105,18 @@
if (cq->notify == IB_CQ_NEXT_COMP ||
(cq->notify == IB_CQ_SOLICITED &&
(solicited || entry->status != IB_WC_SUCCESS))) {
- cq->notify = IB_CQ_NONE;
- cq->triggered++;
+ struct kthread_worker *worker;
/*
* This will cause send_complete() to be called in
* another thread.
*/
- queue_work(qib_cq_wq, &cq->comptask);
+ smp_rmb();
+ worker = cq->dd->worker;
+ if (likely(worker)) {
+ cq->notify = IB_CQ_NONE;
+ cq->triggered++;
+ queue_kthread_work(worker, &cq->comptask);
+ }
}
spin_unlock_irqrestore(&cq->lock, flags);
@@ -163,7 +171,7 @@
return npolled;
}
-static void send_complete(struct work_struct *work)
+static void send_complete(struct kthread_work *work)
{
struct qib_cq *cq = container_of(work, struct qib_cq, comptask);
@@ -287,11 +295,12 @@
* The number of entries should be >= the number requested or return
* an error.
*/
+ cq->dd = dd_from_dev(dev);
cq->ibcq.cqe = entries;
cq->notify = IB_CQ_NONE;
cq->triggered = 0;
spin_lock_init(&cq->lock);
- INIT_WORK(&cq->comptask, send_complete);
+ init_kthread_work(&cq->comptask, send_complete);
wc->head = 0;
wc->tail = 0;
cq->queue = wc;
@@ -323,7 +332,7 @@
struct qib_ibdev *dev = to_idev(ibcq->device);
struct qib_cq *cq = to_icq(ibcq);
- flush_work(&cq->comptask);
+ flush_kthread_work(&cq->comptask);
spin_lock(&dev->n_cqs_lock);
dev->n_cqs_allocated--;
spin_unlock(&dev->n_cqs_lock);
@@ -483,3 +492,49 @@
bail:
return ret;
}
+
+int qib_cq_init(struct qib_devdata *dd)
+{
+ int ret = 0;
+ int cpu;
+ struct task_struct *task;
+
+ if (dd->worker)
+ return 0;
+ dd->worker = kzalloc(sizeof(*dd->worker), GFP_KERNEL);
+ if (!dd->worker)
+ return -ENOMEM;
+ init_kthread_worker(dd->worker);
+ task = kthread_create_on_node(
+ kthread_worker_fn,
+ dd->worker,
+ dd->assigned_node_id,
+ "qib_cq%d", dd->unit);
+ if (IS_ERR(task))
+ goto task_fail;
+ cpu = cpumask_first(cpumask_of_node(dd->assigned_node_id));
+ kthread_bind(task, cpu);
+ wake_up_process(task);
+out:
+ return ret;
+task_fail:
+ ret = PTR_ERR(task);
+ kfree(dd->worker);
+ dd->worker = NULL;
+ goto out;
+}
+
+void qib_cq_exit(struct qib_devdata *dd)
+{
+ struct kthread_worker *worker;
+
+ worker = dd->worker;
+ if (!worker)
+ return;
+ /* blocks future queuing from send_complete() */
+ dd->worker = NULL;
+ smp_wmb();
+ flush_kthread_worker(worker);
+ kthread_stop(worker->task);
+ kfree(worker);
+}