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RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs 

Combine contiguous regions of PAGE_SIZE pages into single scatter list
entry while building the scatter table for a umem. This minimizes the
number of the entries in the scatter list and reduces the DMA mapping
overhead, particularly with the IOMMU.

Set default max_seg_size in core for IB devices to 2G and do not combine
if we exceed this limit.

Also, purge npages in struct ib_umem as we now DMA map the umem SGL with
sg_nents and npage computation is not needed. Drivers should now be using
ib_umem_num_pages(), so fix the last stragglers.

Move npages tracking to ib_umem_odp as ODP drivers still need it.

Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Tested-by: Gal Pressman <galpress@amazon.com>
Tested-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Shiraz Saleem 2019-04-02 14:52:52 -05:00 committed by Jason Gunthorpe
parent c7252a6532
commit d10bcf947a
7 changed files with 95 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/infiniband/core/device.c
View File

@ -1089,6 +1089,9 @@ static void setup_dma_device(struct ib_device *device)
WARN_ON_ONCE(!parent);
device->dma_device = parent;
}
/* Setup default max segment size for all IB devices */
dma_set_max_seg_size(device->dma_device, SZ_2G);
}
/*

101
drivers/infiniband/core/umem.c
View File

@ -39,25 +39,22 @@
#include <linux/export.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <rdma/ib_umem_odp.h>
#include "uverbs.h"
static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
struct scatterlist *sg;
struct sg_page_iter sg_iter;
struct page *page;
int i;
if (umem->nmap > 0)
ib_dma_unmap_sg(dev, umem->sg_head.sgl,
umem->npages,
ib_dma_unmap_sg(dev, umem->sg_head.sgl, umem->sg_nents,
DMA_BIDIRECTIONAL);
for_each_sg(umem->sg_head.sgl, sg, umem->npages, i) {
page = sg_page(sg);
for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
page = sg_page_iter_page(&sg_iter);
if (!PageDirty(page) && umem->writable && dirty)
set_page_dirty_lock(page);
put_page(page);
@ -66,6 +63,69 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
sg_free_table(&umem->sg_head);
}
/* ib_umem_add_sg_table - Add N contiguous pages to scatter table
*
* sg: current scatterlist entry
* page_list: array of npage struct page pointers
* npages: number of pages in page_list
* max_seg_sz: maximum segment size in bytes
* nents: [out] number of entries in the scatterlist
*
* Return new end of scatterlist
*/
static struct scatterlist *ib_umem_add_sg_table(struct scatterlist *sg,
struct page **page_list,
unsigned long npages,
unsigned int max_seg_sz,
int *nents)
{
unsigned long first_pfn;
unsigned long i = 0;
bool update_cur_sg = false;
bool first = !sg_page(sg);
/* Check if new page_list is contiguous with end of previous page_list.
* sg->length here is a multiple of PAGE_SIZE and sg->offset is 0.
*/
if (!first && (page_to_pfn(sg_page(sg)) + (sg->length >> PAGE_SHIFT) ==
page_to_pfn(page_list[0])))
update_cur_sg = true;
while (i != npages) {
unsigned long len;
struct page *first_page = page_list[i];
first_pfn = page_to_pfn(first_page);
/* Compute the number of contiguous pages we have starting
* at i
*/
for (len = 0; i != npages &&
first_pfn + len == page_to_pfn(page_list[i]);
len++)
i++;
/* Squash N contiguous pages from page_list into current sge */
if (update_cur_sg &&
((max_seg_sz - sg->length) >= (len << PAGE_SHIFT))) {
sg_set_page(sg, sg_page(sg),
sg->length + (len << PAGE_SHIFT), 0);
update_cur_sg = false;
continue;
}
/* Squash N contiguous pages into next sge or first sge */
if (!first)
sg = sg_next(sg);
(*nents)++;
sg_set_page(sg, first_page, len << PAGE_SHIFT, 0);
first = false;
}
return sg;
}
/**
* ib_umem_get - Pin and DMA map userspace memory.
*
@ -93,7 +153,7 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
int ret;
int i;
unsigned long dma_attrs = 0;
struct scatterlist *sg, *sg_list_start;
struct scatterlist *sg;
unsigned int gup_flags = FOLL_WRITE;
if (!udata)
@ -190,7 +250,7 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
if (!umem->writable)
gup_flags |= FOLL_FORCE;
sg_list_start = umem->sg_head.sgl;
sg = umem->sg_head.sgl;
while (npages) {
down_read(&mm->mmap_sem);
@ -203,28 +263,29 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
goto umem_release;
}
umem->npages += ret;
cur_base += ret * PAGE_SIZE;
npages -= ret;
sg = ib_umem_add_sg_table(sg, page_list, ret,
dma_get_max_seg_size(context->device->dma_device),
&umem->sg_nents);
/* Continue to hold the mmap_sem as vma_list access
* needs to be protected.
*/
for_each_sg(sg_list_start, sg, ret, i) {
for (i = 0; i < ret && umem->hugetlb; i++) {
if (vma_list && !is_vm_hugetlb_page(vma_list[i]))
umem->hugetlb = 0;
sg_set_page(sg, page_list[i], PAGE_SIZE, 0);
}
up_read(&mm->mmap_sem);
/* preparing for next loop */
sg_list_start = sg;
up_read(&mm->mmap_sem);
}
sg_mark_end(sg);
umem->nmap = ib_dma_map_sg_attrs(context->device,
umem->sg_head.sgl,
umem->npages,
umem->sg_nents,
DMA_BIDIRECTIONAL,
dma_attrs);
@ -320,8 +381,8 @@ int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
return -EINVAL;
}
ret = sg_pcopy_to_buffer(umem->sg_head.sgl, umem->npages, dst, length,
offset + ib_umem_offset(umem));
ret = sg_pcopy_to_buffer(umem->sg_head.sgl, ib_umem_num_pages(umem),
dst, length, offset + ib_umem_offset(umem));
if (ret < 0)
return ret;

4
drivers/infiniband/core/umem_odp.c
View File

@ -526,7 +526,7 @@ static int ib_umem_odp_map_dma_single_page(
}
umem_odp->dma_list[page_index] = dma_addr | access_mask;
umem_odp->page_list[page_index] = page;
umem->npages++;
umem_odp->npages++;
} else if (umem_odp->page_list[page_index] == page) {
umem_odp->dma_list[page_index] |= access_mask;
} else {
@ -752,7 +752,7 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
}
umem_odp->page_list[idx] = NULL;
umem_odp->dma_list[idx] = 0;
umem->npages--;
umem_odp->npages--;
}
}
mutex_unlock(&umem_odp->umem_mutex);

2
drivers/infiniband/hw/mlx5/odp.c
View File

@ -288,7 +288,7 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
ib_umem_odp_unmap_dma_pages(umem_odp, start, end);
if (unlikely(!umem->npages && mr->parent &&
if (unlikely(!umem_odp->npages && mr->parent &&
!umem_odp->dying)) {
WRITE_ONCE(umem_odp->dying, 1);
atomic_inc(&mr->parent->num_leaf_free);

11
drivers/infiniband/hw/vmw_pvrdma/pvrdma_mr.c
View File

@ -119,7 +119,7 @@ struct ib_mr *pvrdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
union pvrdma_cmd_resp rsp;
struct pvrdma_cmd_create_mr *cmd = &req.create_mr;
struct pvrdma_cmd_create_mr_resp *resp = &rsp.create_mr_resp;
int ret;
int ret, npages;
if (length == 0 || length > dev->dsr->caps.max_mr_size) {
dev_warn(&dev->pdev->dev, "invalid mem region length\n");
@ -133,9 +133,10 @@ struct ib_mr *pvrdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
return ERR_CAST(umem);
}
if (umem->npages < 0 || umem->npages > PVRDMA_PAGE_DIR_MAX_PAGES) {
npages = ib_umem_num_pages(umem);
if (npages < 0 || npages > PVRDMA_PAGE_DIR_MAX_PAGES) {
dev_warn(&dev->pdev->dev, "overflow %d pages in mem region\n",
umem->npages);
npages);
ret = -EINVAL;
goto err_umem;
}
@ -150,7 +151,7 @@ struct ib_mr *pvrdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
mr->mmr.size = length;
mr->umem = umem;
ret = pvrdma_page_dir_init(dev, &mr->pdir, umem->npages, false);
ret = pvrdma_page_dir_init(dev, &mr->pdir, npages, false);
if (ret) {
dev_warn(&dev->pdev->dev,
"could not allocate page directory\n");
@ -167,7 +168,7 @@ struct ib_mr *pvrdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
cmd->length = length;
cmd->pd_handle = to_vpd(pd)->pd_handle;
cmd->access_flags = access_flags;
cmd->nchunks = umem->npages;
cmd->nchunks = npages;
cmd->pdir_dma = mr->pdir.dir_dma;
ret = pvrdma_cmd_post(dev, &req, &rsp, PVRDMA_CMD_CREATE_MR_RESP);

2
include/rdma/ib_umem.h
View File

@ -53,7 +53,7 @@ struct ib_umem {
struct work_struct work;
struct sg_table sg_head;
int nmap;
int npages;
unsigned int sg_nents;
};
/* Returns the offset of the umem start relative to the first page. */

1
include/rdma/ib_umem_odp.h
View File

@ -69,6 +69,7 @@ struct ib_umem_odp {
int notifiers_seq;
int notifiers_count;
int npages;
/* Tree tracking */
struct umem_odp_node interval_tree;