On 3/21/19 4:12 PM, Christoph Hellwig wrote:
> We'll have a better way to optimize for small I/O that doesn't
> require it soon, so remove the existing inline_sg case to make that
> optimization easier to implement.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> drivers/nvme/host/pci.c | 38 ++++++--------------------------------
> 1 file changed, 6 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index cf29d079ad5b..c6047935e825 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -223,7 +223,6 @@ struct nvme_iod {
> dma_addr_t first_dma;
> dma_addr_t meta_dma;
> struct scatterlist *sg;
> - struct scatterlist inline_sg[0];
> };
>
> /*
> @@ -370,12 +369,6 @@ static bool nvme_dbbuf_update_and_check_event(u16 value, u32 *dbbuf_db,
> return true;
> }
>
> -/*
> - * Max size of iod being embedded in the request payload
> - */
> -#define NVME_INT_PAGES 2
> -#define NVME_INT_BYTES(dev) (NVME_INT_PAGES * (dev)->ctrl.page_size)
> -
> /*
> * Will slightly overestimate the number of pages needed. This is OK
> * as it only leads to a small amount of wasted memory for the lifetime of
> @@ -410,15 +403,6 @@ static unsigned int nvme_pci_iod_alloc_size(struct nvme_dev *dev,
> return alloc_size + sizeof(struct scatterlist) * nseg;
> }
>
> -static unsigned int nvme_pci_cmd_size(struct nvme_dev *dev, bool use_sgl)
> -{
> - unsigned int alloc_size = nvme_pci_iod_alloc_size(dev,
> - NVME_INT_BYTES(dev), NVME_INT_PAGES,
> - use_sgl);
> -
> - return sizeof(struct nvme_iod) + alloc_size;
> -}
> -
> static int nvme_admin_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
> unsigned int hctx_idx)
> {
> @@ -621,8 +605,7 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
> dma_addr = next_dma_addr;
> }
>
> - if (iod->sg != iod->inline_sg)
> - mempool_free(iod->sg, dev->iod_mempool);
> + mempool_free(iod->sg, dev->iod_mempool);
> }
>
> static void nvme_print_sgl(struct scatterlist *sgl, int nents)
> @@ -822,14 +805,9 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
> blk_status_t ret = BLK_STS_IOERR;
> int nr_mapped;
>
> - if (blk_rq_payload_bytes(req) > NVME_INT_BYTES(dev) ||
> - blk_rq_nr_phys_segments(req) > NVME_INT_PAGES) {
> - iod->sg = mempool_alloc(dev->iod_mempool, GFP_ATOMIC);
> - if (!iod->sg)
> - return BLK_STS_RESOURCE;
> - } else {
> - iod->sg = iod->inline_sg;
> - }
> + iod->sg = mempool_alloc(dev->iod_mempool, GFP_ATOMIC);
> + if (!iod->sg)
> + return BLK_STS_RESOURCE;
>
> iod->use_sgl = nvme_pci_use_sgls(dev, req);
>
> @@ -1619,7 +1597,7 @@ static int nvme_alloc_admin_tags(struct nvme_dev *dev)
> dev->admin_tagset.queue_depth = NVME_AQ_MQ_TAG_DEPTH;
> dev->admin_tagset.timeout = ADMIN_TIMEOUT;
> dev->admin_tagset.numa_node = dev_to_node(dev->dev);
> - dev->admin_tagset.cmd_size = nvme_pci_cmd_size(dev, false);
> + dev->admin_tagset.cmd_size = sizeof(struct nvme_iod);
> dev->admin_tagset.flags = BLK_MQ_F_NO_SCHED;
> dev->admin_tagset.driver_data = dev;
>
> @@ -2266,11 +2244,7 @@ static int nvme_dev_add(struct nvme_dev *dev)
> dev->tagset.numa_node = dev_to_node(dev->dev);
> dev->tagset.queue_depth =
> min_t(int, dev->q_depth, BLK_MQ_MAX_DEPTH) - 1;
> - dev->tagset.cmd_size = nvme_pci_cmd_size(dev, false);
> - if ((dev->ctrl.sgls & ((1 << 0) | (1 << 1))) && sgl_threshold) {
> - dev->tagset.cmd_size = max(dev->tagset.cmd_size,
> - nvme_pci_cmd_size(dev, true));
> - }
> + dev->tagset.cmd_size = sizeof(struct nvme_iod);
> dev->tagset.flags = BLK_MQ_F_SHOULD_MERGE;
> dev->tagset.driver_data = dev;
>
>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
