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From: Jason Gunthorpe <jgg@nvidia.com>
To: Doug Ledford <dledford@redhat.com>, <linux-rdma@vger.kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>,
	Shiraz Saleem <shiraz.saleem@intel.com>
Subject: [PATCH v2 01/17] RDMA/umem: Fix ib_umem_find_best_pgsz() for mappings that cross a page boundary
Date: Fri, 4 Sep 2020 19:41:42 -0300	[thread overview]
Message-ID: <1-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.com> (raw)
In-Reply-To: <0-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.com>

It is possible for a single SGL to span an aligned boundary, eg if the SGL
is

  61440 -> 90112

Then the length is 28672, which currently limits the block size to
32k. With a 32k page size the two covering blocks will be:

  32768->65536 and 65536->98304

However, the correct answer is a 128K block size which will span the whole
28672 bytes in a single block.

Instead of limiting based on length figure out which high IOVA bits don't
change between the start and end addresses. That is the highest useful
page size.

Fixes: 4a35339958f1 ("RDMA/umem: Add API to find best driver supported page size in an MR")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
---
 drivers/infiniband/core/umem.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 831bff8d52e547..09539dd764ec05 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -156,8 +156,13 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 		return 0;
 
 	va = virt;
-	/* max page size not to exceed MR length */
-	mask = roundup_pow_of_two(umem->length);
+	/* The best result is the smallest page size that results in the minimum
+	 * number of required pages. Compute the largest page size that could
+	 * work based on VA address bits that don't change.
+	 */
+	mask = pgsz_bitmap &
+	       GENMASK(BITS_PER_LONG - 1,
+		       bits_per((umem->length - 1 + virt) ^ virt));
 	/* offset into first SGL */
 	pgoff = umem->address & ~PAGE_MASK;
 
-- 
2.28.0


  reply	other threads:[~2020-09-04 22:42 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 22:41 [PATCH v2 00/17] RDMA: Improve use of umem in DMA drivers Jason Gunthorpe
2020-09-04 22:41 ` Jason Gunthorpe [this message]
2020-09-04 22:41 ` [PATCH v2 02/17] RDMA/umem: Prevent small pages from being returned by ib_umem_find_best_pgsz() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 03/17] RDMA/umem: Use simpler logic for ib_umem_find_best_pgsz() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 04/17] RDMA/umem: Add rdma_umem_for_each_dma_block() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 05/17] RDMA/umem: Replace for_each_sg_dma_page with rdma_umem_for_each_dma_block Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 06/17] RDMA/umem: Split ib_umem_num_pages() into ib_umem_num_dma_blocks() Jason Gunthorpe
2020-09-07 12:16   ` Gal Pressman
2020-09-11 13:21   ` Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 07/17] RDMA/efa: Use ib_umem_num_dma_pages() Jason Gunthorpe
2020-09-07 12:19   ` Gal Pressman
2020-09-08 13:48     ` Jason Gunthorpe
2020-09-09  8:18       ` Gal Pressman
2020-09-09 11:14         ` Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 08/17] RDMA/i40iw: " Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 09/17] RDMA/qedr: Use rdma_umem_for_each_dma_block() instead of open-coding Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 10/17] RDMA/qedr: Use ib_umem_num_dma_blocks() instead of ib_umem_page_count() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 11/17] RDMA/bnxt: Do not use ib_umem_page_count() or ib_umem_num_pages() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 12/17] RDMA/hns: Use ib_umem_num_dma_blocks() instead of opencoding Jason Gunthorpe
2020-09-07  8:11   ` liweihang
2020-09-04 22:41 ` [PATCH v2 13/17] RDMA/ocrdma: Use ib_umem_num_dma_blocks() instead of ib_umem_page_count() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 14/17] RDMA/pvrdma: " Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 15/17] RDMA/mlx4: Use ib_umem_num_dma_blocks() Jason Gunthorpe
2020-09-04 22:41 ` [PATCH v2 16/17] RDMA/qedr: Remove fbo and zbva from the MR Jason Gunthorpe
2020-09-06  8:01   ` [EXT] " Michal Kalderon
2020-09-04 22:41 ` [PATCH v2 17/17] RDMA/ocrdma: Remove fbo from MR Jason Gunthorpe
2020-09-06  7:21   ` Leon Romanovsky
2020-09-09 18:38 ` [PATCH v2 00/17] RDMA: Improve use of umem in DMA drivers Jason Gunthorpe

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