On 12/8/20 9:29 AM, Joao Martins wrote:
Take advantage of the newly added unpin_user_pages() batched
refcount update, by calculating a page array from an SGL
(same size as the one used in ib_mem_get()) and call
unpin_user_pages() with that.
unpin_user_pages() will check on consecutive pages that belong
to the same compound page set and batch the refcount update in
a single write.
Running a test program which calls mr reg/unreg on a 1G in size
and measures cost of both operations together (in a guest using rxe)
with device-dax and hugetlbfs:
Before:
159 rounds in 5.027 sec: 31617.923 usec / round (device-dax)
466 rounds in 5.009 sec: 10748.456 usec / round (hugetlbfs)
After:
305 rounds in 5.010 sec: 16426.047 usec / round (device-dax)
1073 rounds in 5.004 sec: 4663.622 usec / round (hugetlbfs)
We also see similar improvements on a setup with pmem and RDMA hardware.
Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
---
drivers/infiniband/core/umem.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index e9fecbdf391b..493cfdcf7381 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -44,20 +44,40 @@
#include "uverbs.h"
+#define PAGES_PER_LIST (PAGE_SIZE / sizeof(struct page *))
I was going to maybe suggest that this item, and the "bool make_dirty" cleanup,
be a separate patch, because they are just cleanups. But the memory allocation issue
below might make that whole (minor) point obsolete.
+
static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
+ bool make_dirty = umem->writable && dirty;
+ struct page **page_list = NULL;
struct sg_page_iter sg_iter;
+ unsigned long nr = 0;
struct page *page;
+ page_list = (struct page **) __get_free_page(GFP_KERNEL);
Yeah, allocating memory in a free/release path is not good. btw, for future use,
I see that kmalloc() is generally recommended these days (that's a change), when
you want a pointer to storage, as opposed to wanting struct pages:
https://lore.kernel.org/lkml/CA+55aFwyxJ+TOpaJZnC5MPJ-25xbLAEu8iJP8zTYhmA3LXFF8Q@xxxxxxxxxxxxxx/
+
if (umem->nmap > 0)
ib_dma_unmap_sg(dev, umem->sg_head.sgl, umem->sg_nents,
DMA_BIDIRECTIONAL);
for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
page = sg_page_iter_page(&sg_iter);
- unpin_user_pages_dirty_lock(&page, 1, umem->writable && dirty);
+ if (page_list)
+ page_list[nr++] = page;
+
+ if (!page_list) {
+ unpin_user_pages_dirty_lock(&page, 1, make_dirty);
+ } else if (nr == PAGES_PER_LIST) {
+ unpin_user_pages_dirty_lock(page_list, nr, make_dirty);
+ nr = 0;
+ }
}
+ if (nr)
+ unpin_user_pages_dirty_lock(page_list, nr, make_dirty);
+
+ if (page_list)
+ free_page((unsigned long) page_list);
sg_free_table(&umem->sg_head);
}
@@ -212,8 +232,7 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
cond_resched();
ret = pin_user_pages_fast(cur_base,
min_t(unsigned long, npages,
- PAGE_SIZE /
- sizeof(struct page *)),
+ PAGES_PER_LIST),
gup_flags | FOLL_LONGTERM, page_list);
if (ret < 0)
goto umem_release;
thanks,
--
John Hubbard
NVIDIA
