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>
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@ -775,7 +775,7 @@ static int nvme_process_cq(struct nvme_queue *nvmeq)
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if (head == nvmeq->cq_head && phase == nvmeq->cq_phase)
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return 0;
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writel(head, nvmeq->q_db + (1 << nvmeq->dev->db_stride));
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writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
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nvmeq->cq_head = head;
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nvmeq->cq_phase = phase;
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@ -1113,7 +1113,7 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
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init_waitqueue_head(&nvmeq->sq_full);
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init_waitqueue_entry(&nvmeq->sq_cong_wait, nvme_thread);
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bio_list_init(&nvmeq->sq_cong);
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nvmeq->q_db = &dev->dbs[qid << (dev->db_stride + 1)];
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nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
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nvmeq->q_depth = depth;
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nvmeq->cq_vector = vector;
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nvmeq->q_suspended = 1;
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@ -1149,7 +1149,7 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
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nvmeq->sq_tail = 0;
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nvmeq->cq_head = 0;
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nvmeq->cq_phase = 1;
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nvmeq->q_db = &dev->dbs[qid << (dev->db_stride + 1)];
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nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
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memset(nvmeq->cmdid_data, 0, extra);
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memset((void *)nvmeq->cqes, 0, CQ_SIZE(nvmeq->q_depth));
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nvme_cancel_ios(nvmeq, false);
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@ -1741,7 +1741,7 @@ static int set_queue_count(struct nvme_dev *dev, int count)
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static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
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{
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return 4096 + ((nr_io_queues + 1) << (dev->db_stride + 3));
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return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
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}
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static int nvme_setup_io_queues(struct nvme_dev *dev)
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@ -1958,7 +1958,7 @@ static int nvme_dev_map(struct nvme_dev *dev)
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if (!dev->bar)
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goto disable;
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dev->db_stride = NVME_CAP_STRIDE(readq(&dev->bar->cap));
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dev->db_stride = 1 << NVME_CAP_STRIDE(readq(&dev->bar->cap));
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dev->dbs = ((void __iomem *)dev->bar) + 4096;
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return 0;
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@ -80,7 +80,7 @@ struct nvme_dev {
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struct dma_pool *prp_small_pool;
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int instance;
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int queue_count;
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int db_stride;
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u32 db_stride;
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u32 ctrl_config;
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struct msix_entry *entry;
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struct nvme_bar __iomem *bar;
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