From: Caleb Sander Mateos Date: Mon, 12 May 2025 13:50:40 +0000 (+0200) Subject: nvme-pci: make PRP list DMA pools per-NUMA-node X-Git-Tag: v6.16-rc1~216^2~15^2~11 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d977506f8863807129d7a11f4057dfb1b38085ea;p=thirdparty%2Fkernel%2Flinux.git nvme-pci: make PRP list DMA pools per-NUMA-node NVMe commands with over 8 KB of discontiguous data allocate PRP list pages from the per-nvme_device dma_pool prp_page_pool or prp_small_pool. Each call to dma_pool_alloc() and dma_pool_free() takes the per-dma_pool spinlock. These device-global spinlocks are a significant source of contention when many CPUs are submitting to the same NVMe devices. On a workload issuing 32 KB reads from 16 CPUs (8 hypertwin pairs) across 2 NUMA nodes to 23 NVMe devices, we observed 2.4% of CPU time spent in _raw_spin_lock_irqsave called from dma_pool_alloc and dma_pool_free. Ideally, the dma_pools would be per-hctx to minimize contention. But that could impose considerable resource costs in a system with many NVMe devices and CPUs. As a compromise, allocate per-NUMA-node PRP list DMA pools. Map each nvme_queue to the set of DMA pools corresponding to its device and its hctx's NUMA node. This reduces the _raw_spin_lock_irqsave overhead by about half, to 1.2%. Preventing the sharing of PRP list pages across NUMA nodes also makes them cheaper to initialize. Link: https://lore.kernel.org/linux-nvme/CADUfDZqa=OOTtTTznXRDmBQo1WrFcDw1hBA7XwM7hzJ-hpckcA@mail.gmail.com/T/#u Signed-off-by: Caleb Sander Mateos Reviewed-by: Jens Axboe Reviewed-by: Keith Busch Reviewed-by: Sagi Grimberg Reviewed-by: Kanchan Joshi Signed-off-by: Christoph Hellwig --- diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 30abf134c8866..e6b6b6ee08786 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -112,6 +113,11 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown); static void nvme_delete_io_queues(struct nvme_dev *dev); static void nvme_update_attrs(struct nvme_dev *dev); +struct nvme_prp_dma_pools { + struct dma_pool *large; + struct dma_pool *small; +}; + /* * Represents an NVM Express device. Each nvme_dev is a PCI function. */ @@ -121,8 +127,6 @@ struct nvme_dev { struct blk_mq_tag_set admin_tagset; u32 __iomem *dbs; struct device *dev; - struct dma_pool *prp_page_pool; - struct dma_pool *prp_small_pool; unsigned online_queues; unsigned max_qid; unsigned io_queues[HCTX_MAX_TYPES]; @@ -162,6 +166,7 @@ struct nvme_dev { unsigned int nr_allocated_queues; unsigned int nr_write_queues; unsigned int nr_poll_queues; + struct nvme_prp_dma_pools prp_pools[]; }; static int io_queue_depth_set(const char *val, const struct kernel_param *kp) @@ -191,6 +196,7 @@ static inline struct nvme_dev *to_nvme_dev(struct nvme_ctrl *ctrl) */ struct nvme_queue { struct nvme_dev *dev; + struct nvme_prp_dma_pools prp_pools; spinlock_t sq_lock; void *sq_cmds; /* only used for poll queues: */ @@ -397,15 +403,64 @@ static int nvme_pci_npages_prp(void) return DIV_ROUND_UP(8 * nprps, NVME_CTRL_PAGE_SIZE - 8); } +static struct nvme_prp_dma_pools * +nvme_setup_prp_pools(struct nvme_dev *dev, unsigned numa_node) +{ + struct nvme_prp_dma_pools *prp_pools = &dev->prp_pools[numa_node]; + size_t small_align = 256; + + if (prp_pools->small) + return prp_pools; /* already initialized */ + + prp_pools->large = dma_pool_create_node("prp list page", dev->dev, + NVME_CTRL_PAGE_SIZE, + NVME_CTRL_PAGE_SIZE, 0, + numa_node); + if (!prp_pools->large) + return ERR_PTR(-ENOMEM); + + if (dev->ctrl.quirks & NVME_QUIRK_DMAPOOL_ALIGN_512) + small_align = 512; + + /* Optimisation for I/Os between 4k and 128k */ + prp_pools->small = dma_pool_create_node("prp list 256", dev->dev, + 256, small_align, 0, numa_node); + if (!prp_pools->small) { + dma_pool_destroy(prp_pools->large); + prp_pools->large = NULL; + return ERR_PTR(-ENOMEM); + } + + return prp_pools; +} + +static void nvme_release_prp_pools(struct nvme_dev *dev) +{ + unsigned i; + + for (i = 0; i < nr_node_ids; i++) { + struct nvme_prp_dma_pools *prp_pools = &dev->prp_pools[i]; + + dma_pool_destroy(prp_pools->large); + dma_pool_destroy(prp_pools->small); + } +} + static int nvme_init_hctx_common(struct blk_mq_hw_ctx *hctx, void *data, unsigned qid) { struct nvme_dev *dev = to_nvme_dev(data); struct nvme_queue *nvmeq = &dev->queues[qid]; + struct nvme_prp_dma_pools *prp_pools; struct blk_mq_tags *tags; tags = qid ? dev->tagset.tags[qid - 1] : dev->admin_tagset.tags[0]; WARN_ON(tags != hctx->tags); + prp_pools = nvme_setup_prp_pools(dev, hctx->numa_node); + if (IS_ERR(prp_pools)) + return PTR_ERR(prp_pools); + + nvmeq->prp_pools = *prp_pools; hctx->driver_data = nvmeq; return 0; } @@ -539,7 +594,7 @@ static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req, return true; } -static void nvme_free_prps(struct nvme_dev *dev, struct request *req) +static void nvme_free_prps(struct nvme_queue *nvmeq, struct request *req) { const int last_prp = NVME_CTRL_PAGE_SIZE / sizeof(__le64) - 1; struct nvme_iod *iod = blk_mq_rq_to_pdu(req); @@ -550,12 +605,13 @@ static void nvme_free_prps(struct nvme_dev *dev, struct request *req) __le64 *prp_list = iod->list[i].prp_list; dma_addr_t next_dma_addr = le64_to_cpu(prp_list[last_prp]); - dma_pool_free(dev->prp_page_pool, prp_list, dma_addr); + dma_pool_free(nvmeq->prp_pools.large, prp_list, dma_addr); dma_addr = next_dma_addr; } } -static void nvme_unmap_data(struct nvme_dev *dev, struct request *req) +static void nvme_unmap_data(struct nvme_dev *dev, struct nvme_queue *nvmeq, + struct request *req) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); @@ -570,13 +626,13 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req) dma_unmap_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req), 0); if (iod->nr_allocations == 0) - dma_pool_free(dev->prp_small_pool, iod->list[0].sg_list, + dma_pool_free(nvmeq->prp_pools.small, iod->list[0].sg_list, iod->first_dma); else if (iod->nr_allocations == 1) - dma_pool_free(dev->prp_page_pool, iod->list[0].sg_list, + dma_pool_free(nvmeq->prp_pools.large, iod->list[0].sg_list, iod->first_dma); else - nvme_free_prps(dev, req); + nvme_free_prps(nvmeq, req); mempool_free(iod->sgt.sgl, dev->iod_mempool); } @@ -594,7 +650,7 @@ static void nvme_print_sgl(struct scatterlist *sgl, int nents) } } -static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev, +static blk_status_t nvme_pci_setup_prps(struct nvme_queue *nvmeq, struct request *req, struct nvme_rw_command *cmnd) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); @@ -630,10 +686,10 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev, nprps = DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE); if (nprps <= (256 / 8)) { - pool = dev->prp_small_pool; + pool = nvmeq->prp_pools.small; iod->nr_allocations = 0; } else { - pool = dev->prp_page_pool; + pool = nvmeq->prp_pools.large; iod->nr_allocations = 1; } @@ -675,7 +731,7 @@ done: cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma); return BLK_STS_OK; free_prps: - nvme_free_prps(dev, req); + nvme_free_prps(nvmeq, req); return BLK_STS_RESOURCE; bad_sgl: WARN(DO_ONCE(nvme_print_sgl, iod->sgt.sgl, iod->sgt.nents), @@ -700,7 +756,7 @@ static void nvme_pci_sgl_set_seg(struct nvme_sgl_desc *sge, sge->type = NVME_SGL_FMT_LAST_SEG_DESC << 4; } -static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev, +static blk_status_t nvme_pci_setup_sgls(struct nvme_queue *nvmeq, struct request *req, struct nvme_rw_command *cmd) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); @@ -720,10 +776,10 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev, } if (entries <= (256 / sizeof(struct nvme_sgl_desc))) { - pool = dev->prp_small_pool; + pool = nvmeq->prp_pools.small; iod->nr_allocations = 0; } else { - pool = dev->prp_page_pool; + pool = nvmeq->prp_pools.large; iod->nr_allocations = 1; } @@ -787,12 +843,12 @@ static blk_status_t nvme_setup_sgl_simple(struct nvme_dev *dev, static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, struct nvme_command *cmnd) { + struct nvme_queue *nvmeq = req->mq_hctx->driver_data; struct nvme_iod *iod = blk_mq_rq_to_pdu(req); blk_status_t ret = BLK_STS_RESOURCE; int rc; if (blk_rq_nr_phys_segments(req) == 1) { - struct nvme_queue *nvmeq = req->mq_hctx->driver_data; struct bio_vec bv = req_bvec(req); if (!is_pci_p2pdma_page(bv.bv_page)) { @@ -827,9 +883,9 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, } if (nvme_pci_use_sgls(dev, req, iod->sgt.nents)) - ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw); + ret = nvme_pci_setup_sgls(nvmeq, req, &cmnd->rw); else - ret = nvme_pci_setup_prps(dev, req, &cmnd->rw); + ret = nvme_pci_setup_prps(nvmeq, req, &cmnd->rw); if (ret != BLK_STS_OK) goto out_unmap_sg; return BLK_STS_OK; @@ -844,6 +900,7 @@ out_free_sg: static blk_status_t nvme_pci_setup_meta_sgls(struct nvme_dev *dev, struct request *req) { + struct nvme_queue *nvmeq = req->mq_hctx->driver_data; struct nvme_iod *iod = blk_mq_rq_to_pdu(req); struct nvme_rw_command *cmnd = &iod->cmd.rw; struct nvme_sgl_desc *sg_list; @@ -867,7 +924,7 @@ static blk_status_t nvme_pci_setup_meta_sgls(struct nvme_dev *dev, if (rc) goto out_free_sg; - sg_list = dma_pool_alloc(dev->prp_small_pool, GFP_ATOMIC, &sgl_dma); + sg_list = dma_pool_alloc(nvmeq->prp_pools.small, GFP_ATOMIC, &sgl_dma); if (!sg_list) goto out_unmap_sg; @@ -949,7 +1006,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req) return BLK_STS_OK; out_unmap_data: if (blk_rq_nr_phys_segments(req)) - nvme_unmap_data(dev, req); + nvme_unmap_data(dev, req->mq_hctx->driver_data, req); out_free_cmd: nvme_cleanup_cmd(req); return ret; @@ -1039,6 +1096,7 @@ static void nvme_queue_rqs(struct rq_list *rqlist) } static __always_inline void nvme_unmap_metadata(struct nvme_dev *dev, + struct nvme_queue *nvmeq, struct request *req) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); @@ -1050,7 +1108,7 @@ static __always_inline void nvme_unmap_metadata(struct nvme_dev *dev, return; } - dma_pool_free(dev->prp_small_pool, iod->meta_list.sg_list, + dma_pool_free(nvmeq->prp_pools.small, iod->meta_list.sg_list, iod->meta_dma); dma_unmap_sgtable(dev->dev, &iod->meta_sgt, rq_dma_dir(req), 0); mempool_free(iod->meta_sgt.sgl, dev->iod_meta_mempool); @@ -1062,10 +1120,10 @@ static __always_inline void nvme_pci_unmap_rq(struct request *req) struct nvme_dev *dev = nvmeq->dev; if (blk_integrity_rq(req)) - nvme_unmap_metadata(dev, req); + nvme_unmap_metadata(dev, nvmeq, req); if (blk_rq_nr_phys_segments(req)) - nvme_unmap_data(dev, req); + nvme_unmap_data(dev, nvmeq, req); } static void nvme_pci_complete_rq(struct request *req) @@ -2842,35 +2900,6 @@ static int nvme_disable_prepare_reset(struct nvme_dev *dev, bool shutdown) return 0; } -static int nvme_setup_prp_pools(struct nvme_dev *dev) -{ - size_t small_align = 256; - - dev->prp_page_pool = dma_pool_create("prp list page", dev->dev, - NVME_CTRL_PAGE_SIZE, - NVME_CTRL_PAGE_SIZE, 0); - if (!dev->prp_page_pool) - return -ENOMEM; - - if (dev->ctrl.quirks & NVME_QUIRK_DMAPOOL_ALIGN_512) - small_align = 512; - - /* Optimisation for I/Os between 4k and 128k */ - dev->prp_small_pool = dma_pool_create("prp list 256", dev->dev, - 256, small_align, 0); - if (!dev->prp_small_pool) { - dma_pool_destroy(dev->prp_page_pool); - return -ENOMEM; - } - return 0; -} - -static void nvme_release_prp_pools(struct nvme_dev *dev) -{ - dma_pool_destroy(dev->prp_page_pool); - dma_pool_destroy(dev->prp_small_pool); -} - static int nvme_pci_alloc_iod_mempool(struct nvme_dev *dev) { size_t meta_size = sizeof(struct scatterlist) * (NVME_MAX_META_SEGS + 1); @@ -3185,7 +3214,8 @@ static struct nvme_dev *nvme_pci_alloc_dev(struct pci_dev *pdev, struct nvme_dev *dev; int ret = -ENOMEM; - dev = kzalloc_node(sizeof(*dev), GFP_KERNEL, node); + dev = kzalloc_node(sizeof(*dev) + nr_node_ids * sizeof(*dev->prp_pools), + GFP_KERNEL, node); if (!dev) return ERR_PTR(-ENOMEM); INIT_WORK(&dev->ctrl.reset_work, nvme_reset_work); @@ -3260,13 +3290,9 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id) if (result) goto out_uninit_ctrl; - result = nvme_setup_prp_pools(dev); - if (result) - goto out_dev_unmap; - result = nvme_pci_alloc_iod_mempool(dev); if (result) - goto out_release_prp_pools; + goto out_dev_unmap; dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev)); @@ -3342,8 +3368,6 @@ out_disable: out_release_iod_mempool: mempool_destroy(dev->iod_mempool); mempool_destroy(dev->iod_meta_mempool); -out_release_prp_pools: - nvme_release_prp_pools(dev); out_dev_unmap: nvme_dev_unmap(dev); out_uninit_ctrl: