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Message-ID: <670389227a033bd5b7c5aa55191aac9943244028.1744825142.git.leon@kernel.org>
Date: Fri, 18 Apr 2025 09:47:54 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>,
Jens Axboe <axboe@...nel.dk>,
Christoph Hellwig <hch@....de>,
Keith Busch <kbusch@...nel.org>
Cc: Kanchan Joshi <joshi.k@...sung.com>,
Jake Edge <jake@....net>,
Jonathan Corbet <corbet@....net>,
Jason Gunthorpe <jgg@...pe.ca>,
Zhu Yanjun <zyjzyj2000@...il.com>,
Robin Murphy <robin.murphy@....com>,
Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>,
Sagi Grimberg <sagi@...mberg.me>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Logan Gunthorpe <logang@...tatee.com>,
Yishai Hadas <yishaih@...dia.com>,
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
Kevin Tian <kevin.tian@...el.com>,
Alex Williamson <alex.williamson@...hat.com>,
Jérôme Glisse <jglisse@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-block@...r.kernel.org,
linux-rdma@...r.kernel.org,
iommu@...ts.linux.dev,
linux-nvme@...ts.infradead.org,
linux-pci@...r.kernel.org,
kvm@...r.kernel.org,
linux-mm@...ck.org,
Niklas Schnelle <schnelle@...ux.ibm.com>,
Chuck Lever <chuck.lever@...cle.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Matthew Wilcox <willy@...radead.org>,
Dan Williams <dan.j.williams@...el.com>,
Chaitanya Kulkarni <kch@...dia.com>,
Nitesh Shetty <nj.shetty@...sung.com>,
Leon Romanovsky <leonro@...dia.com>
Subject: [PATCH v8 24/24] nvme-pci: optimize single-segment handling
From: Kanchan Joshi <joshi.k@...sung.com>
blk_rq_dma_map API is costly for single-segment requests.
Avoid using it and map the bio_vec directly.
Signed-off-by: Kanchan Joshi <joshi.k@...sung.com>
Signed-off-by: Nitesh Shetty <nj.shetty@...sung.com>
Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
drivers/nvme/host/pci.c | 65 +++++++++++++++++++++++++++++++++++++----
1 file changed, 60 insertions(+), 5 deletions(-)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 8d99a8f871ea..cf020de82962 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -216,6 +216,11 @@ struct nvme_queue {
struct completion delete_done;
};
+enum {
+ IOD_LARGE_DESCRIPTORS = 1, /* uses the full page sized descriptor pool */
+ IOD_SINGLE_SEGMENT = 2, /* single segment dma mapping */
+};
+
/*
* The nvme_iod describes the data in an I/O.
*/
@@ -224,7 +229,7 @@ struct nvme_iod {
struct nvme_command cmd;
bool aborted;
u8 nr_descriptors; /* # of PRP/SGL descriptors */
- bool large_descriptors; /* uses the full page sized descriptor pool */
+ unsigned int flags;
unsigned int total_len; /* length of the entire transfer */
unsigned int total_meta_len; /* length of the entire metadata transfer */
dma_addr_t meta_dma;
@@ -529,7 +534,7 @@ static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req,
static inline struct dma_pool *nvme_dma_pool(struct nvme_dev *dev,
struct nvme_iod *iod)
{
- if (iod->large_descriptors)
+ if (iod->flags & IOD_LARGE_DESCRIPTORS)
return dev->prp_page_pool;
return dev->prp_small_pool;
}
@@ -630,6 +635,15 @@ static void nvme_free_sgls(struct nvme_dev *dev, struct request *req)
static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
{
struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+ unsigned int nr_segments = blk_rq_nr_phys_segments(req);
+ dma_addr_t dma_addr;
+
+ if (nr_segments == 1 && (iod->flags & IOD_SINGLE_SEGMENT)) {
+ dma_addr = le64_to_cpu(iod->cmd.common.dptr.prp1);
+ dma_unmap_page(dev->dev, dma_addr, iod->total_len,
+ rq_dma_dir(req));
+ return;
+ }
if (!blk_rq_dma_unmap(req, dev->dev, &iod->dma_state, iod->total_len)) {
if (iod->cmd.common.flags & NVME_CMD_SGL_METABUF)
@@ -642,6 +656,41 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
nvme_free_descriptors(dev, req);
}
+static bool nvme_try_setup_prp_simple(struct nvme_dev *dev, struct request *req,
+ struct nvme_rw_command *cmnd,
+ struct blk_dma_iter *iter)
+{
+ struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+ struct bio_vec bv = req_bvec(req);
+ unsigned int first_prp_len;
+
+ if (is_pci_p2pdma_page(bv.bv_page))
+ return false;
+ if ((bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1)) + bv.bv_len >
+ NVME_CTRL_PAGE_SIZE * 2)
+ return false;
+
+ iter->addr = dma_map_bvec(dev->dev, &bv, rq_dma_dir(req), 0);
+ if (dma_mapping_error(dev->dev, iter->addr)) {
+ iter->status = BLK_STS_RESOURCE;
+ goto out;
+ }
+ iod->total_len = bv.bv_len;
+ cmnd->dptr.prp1 = cpu_to_le64(iter->addr);
+
+ first_prp_len = NVME_CTRL_PAGE_SIZE -
+ (bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1));
+ if (bv.bv_len > first_prp_len)
+ cmnd->dptr.prp2 = cpu_to_le64(iter->addr + first_prp_len);
+ else
+ cmnd->dptr.prp2 = 0;
+
+ iter->status = BLK_STS_OK;
+ iod->flags |= IOD_SINGLE_SEGMENT;
+out:
+ return true;
+}
+
static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
struct request *req)
{
@@ -652,6 +701,12 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
dma_addr_t prp1_dma, prp2_dma = 0;
unsigned int prp_len, i;
__le64 *prp_list;
+ unsigned int nr_segments = blk_rq_nr_phys_segments(req);
+
+ if (nr_segments == 1) {
+ if (nvme_try_setup_prp_simple(dev, req, cmnd, &iter))
+ return iter.status;
+ }
if (!blk_rq_dma_map_iter_start(req, dev->dev, &iod->dma_state, &iter))
return iter.status;
@@ -693,7 +748,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
if (DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE) >
NVME_SMALL_DESCRIPTOR_SIZE / sizeof(__le64))
- iod->large_descriptors = true;
+ iod->flags |= IOD_LARGE_DESCRIPTORS;
prp_list = dma_pool_alloc(nvme_dma_pool(dev, iod), GFP_ATOMIC,
&prp2_dma);
@@ -808,7 +863,7 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
}
if (entries > NVME_SMALL_DESCRIPTOR_SIZE / sizeof(*sg_list))
- iod->large_descriptors = true;
+ iod->flags |= IOD_LARGE_DESCRIPTORS;
sg_list = dma_pool_alloc(nvme_dma_pool(dev, iod), GFP_ATOMIC, &sgl_dma);
if (!sg_list)
@@ -932,7 +987,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
iod->aborted = false;
iod->nr_descriptors = 0;
- iod->large_descriptors = false;
+ iod->flags = 0;
iod->total_len = 0;
iod->total_meta_len = 0;
--
2.49.0
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