NVMe: Avoid shift operation when writing cq head doorbell
Changes the type of dev->db_stride to unsigned and changes the value
stored there to be 1 << the current value. Then there is less
calculation to be done at completion time.
Signed-off-by: Haiyan Hu <huhaiyan@huawei.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 26d03fa..073aec9 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -775,7 +775,7 @@
if (head == nvmeq->cq_head && phase == nvmeq->cq_phase)
return 0;
- writel(head, nvmeq->q_db + (1 << nvmeq->dev->db_stride));
+ writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
nvmeq->cq_head = head;
nvmeq->cq_phase = phase;
@@ -1113,7 +1113,7 @@
init_waitqueue_head(&nvmeq->sq_full);
init_waitqueue_entry(&nvmeq->sq_cong_wait, nvme_thread);
bio_list_init(&nvmeq->sq_cong);
- nvmeq->q_db = &dev->dbs[qid << (dev->db_stride + 1)];
+ nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
nvmeq->q_depth = depth;
nvmeq->cq_vector = vector;
nvmeq->q_suspended = 1;
@@ -1149,7 +1149,7 @@
nvmeq->sq_tail = 0;
nvmeq->cq_head = 0;
nvmeq->cq_phase = 1;
- nvmeq->q_db = &dev->dbs[qid << (dev->db_stride + 1)];
+ nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
memset(nvmeq->cmdid_data, 0, extra);
memset((void *)nvmeq->cqes, 0, CQ_SIZE(nvmeq->q_depth));
nvme_cancel_ios(nvmeq, false);
@@ -1741,7 +1741,7 @@
static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
{
- return 4096 + ((nr_io_queues + 1) << (dev->db_stride + 3));
+ return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
}
static int nvme_setup_io_queues(struct nvme_dev *dev)
@@ -1958,7 +1958,7 @@
if (!dev->bar)
goto disable;
- dev->db_stride = NVME_CAP_STRIDE(readq(&dev->bar->cap));
+ dev->db_stride = 1 << NVME_CAP_STRIDE(readq(&dev->bar->cap));
dev->dbs = ((void __iomem *)dev->bar) + 4096;
return 0;