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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>
This commit is contained in:
Haiyan Hu 2013-09-10 11:25:37 +08:00 committed by Matthew Wilcox
parent 2d3c627502
commit b80d5ccca3
2 changed files with 6 additions and 6 deletions
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10
drivers/block/nvme-core.c
View File

@ -775,7 +775,7 @@ static int nvme_process_cq(struct nvme_queue *nvmeq)
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 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
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 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
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 int set_queue_count(struct nvme_dev *dev, int count)
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 @@ static int nvme_dev_map(struct nvme_dev *dev)
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;

2
include/linux/nvme.h
View File

@ -80,7 +80,7 @@ struct nvme_dev {
struct dma_pool *prp_small_pool;
int instance;
int queue_count;
int db_stride;
u32 db_stride;
u32 ctrl_config;
struct msix_entry *entry;
struct nvme_bar __iomem *bar;