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Message-Id: <20241114135335.21327-1-c.gameti@samsung.com>
Date: Thu, 14 Nov 2024 19:23:35 +0530
From: Chinmay Gameti <c.gameti@...sung.com>
To: axboe@...nel.dk, hch@....de, kbusch@...nel.org
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
joshi.k@...sung.com, anuj20.g@...sung.com, nj.shetty@...sung.com,
kundan.kumar@...sung.com, gost.dev@...sung.com, Chinmay Gameti
<c.gameti@...sung.com>
Subject: [PATCH] block: add larger order folio instead of pages for
passthrough I/O
This patch supports adding a large folio to bio for passthrough I/Os,
when mTHP is enabled. Similar to block I/O folio changes [1].
These changes reduce the overhead incurred by bio_map_user_iov for
passthrough I/O.
Perf diff before and after this change:
perf diff for write I/O with 64K block size:
0.84% -0.49% [kernel.kallsyms] [k] bio_map_user_iov
1.23% [kernel.kallsyms] [k] bvec_try_merge_page
0.88% [kernel.kallsyms] [k] bvec_try_merge_hw_page
perf diff for read I/O with 64K block size:
1.74% -1.1% [kernel.kallsyms] [k] bio_map_user_iov
2.39% [kernel.kallsyms] [k] bvec_try_merge_page
1.74% [kernel.kallsyms] [k] bvec_try_merge_hw_page
perf diff for write I/O with 128K block size:
0.84% -0.6% [kernel.kallsyms] [k] bio_map_user_iov
1.49% [kernel.kallsyms] [k] bvec_try_merge_page
1.19% [kernel.kallsyms] [k] bvec_try_merge_hw_page
perf diff for read I/O with 128K block size:
2.35% -1.56% [kernel.kallsyms] [k] bio_map_user_iov
4.53% [kernel.kallsyms] [k] bvec_try_merge_page
3.39% [kernel.kallsyms] [k] bvec_try_merge_hw_page
[1] commit ed9832bc08db ("block: introduce folio awareness and add a
bigger size from folio")
Signed-off-by: Chinmay Gameti <c.gameti@...sung.com>
Signed-off-by: Kundan Kumar <kundan.kumar@...sung.com>
---
block/bio.c | 8 ++++----
block/blk-map.c | 31 +++++++++++++++++++++++--------
include/linux/bio.h | 4 ++++
3 files changed, 31 insertions(+), 12 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 699a78c85c75..50e8b565f368 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1203,10 +1203,10 @@ static int bio_iov_add_folio(struct bio *bio, struct folio *folio, size_t len,
return 0;
}
-static unsigned int get_contig_folio_len(unsigned int *num_pages,
- struct page **pages, unsigned int i,
- struct folio *folio, size_t left,
- size_t offset)
+unsigned int get_contig_folio_len(unsigned int *num_pages,
+ struct page **pages, unsigned int i,
+ struct folio *folio, size_t left,
+ size_t offset)
{
size_t bytes = left;
size_t contig_sz = min_t(size_t, PAGE_SIZE - offset, bytes);
diff --git a/block/blk-map.c b/block/blk-map.c
index b5fd1d857461..216d08c8b0de 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -295,8 +295,9 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
struct page *stack_pages[UIO_FASTIOV];
struct page **pages = stack_pages;
ssize_t bytes;
- size_t offs;
int npages;
+ unsigned int num_pages;
+ size_t offs, folio_offset, len;
if (nr_vecs > ARRAY_SIZE(stack_pages))
pages = NULL;
@@ -313,21 +314,35 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
if (unlikely(offs & queue_dma_alignment(rq->q)))
j = 0;
else {
- for (j = 0; j < npages; j++) {
+ for (j = 0; j < npages; j += num_pages) {
struct page *page = pages[j];
- unsigned int n = PAGE_SIZE - offs;
+ struct folio *folio = page_folio(page);
bool same_page = false;
- if (n > bytes)
- n = bytes;
- if (!bio_add_hw_page(rq->q, bio, page, n, offs,
- max_sectors, &same_page))
+ folio_offset = ((size_t)folio_page_idx(folio,
+ page) << PAGE_SHIFT) + offs;
+
+ len = min(folio_size(folio) - folio_offset,
+ (size_t)bytes);
+
+ num_pages = DIV_ROUND_UP(offs + len,
+ PAGE_SIZE);
+
+ if (num_pages > 1)
+ len = get_contig_folio_len(
+ &num_pages, pages, j,
+ folio, (size_t)bytes,
+ offs);
+
+ if (!bio_add_hw_folio(rq->q, bio, folio, len,
+ folio_offset, max_sectors,
+ &same_page))
break;
if (same_page)
bio_release_page(bio, page);
- bytes -= n;
+ bytes -= len;
offs = 0;
}
}
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 60830a6a5939..1e5fbc875ecc 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -422,6 +422,10 @@ void __bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int off);
void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len,
size_t off);
+unsigned int get_contig_folio_len(unsigned int *num_pages,
+ struct page **pages, unsigned int i,
+ struct folio *folio, size_t left,
+ size_t offset);
int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter);
void __bio_release_pages(struct bio *bio, bool mark_dirty);
--
2.34.1
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