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block: drop virtual merging accounting
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Remove virtual merge accounting.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Mikulas Patocka authored and Jens Axboe committed Oct 9, 2008
1 parent 6a421c1 commit b8b3e16
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Showing 3 changed files with 8 additions and 92 deletions.
79 changes: 6 additions & 73 deletions block/blk-merge.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,34 +66,26 @@ void blk_recalc_rq_segments(struct request *rq)
*/
high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
if (high || highprv)
goto new_hw_segment;
goto new_segment;
if (cluster) {
if (seg_size + bv->bv_len > q->max_segment_size)
goto new_segment;
if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
goto new_segment;
if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
goto new_segment;
if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
goto new_hw_segment;

seg_size += bv->bv_len;
hw_seg_size += bv->bv_len;
bvprv = bv;
continue;
}
new_segment:
if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
!BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
hw_seg_size += bv->bv_len;
else {
new_hw_segment:
if (nr_hw_segs == 1 &&
hw_seg_size > rq->bio->bi_hw_front_size)
rq->bio->bi_hw_front_size = hw_seg_size;
hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
nr_hw_segs++;
}
if (nr_hw_segs == 1 &&
hw_seg_size > rq->bio->bi_hw_front_size)
rq->bio->bi_hw_front_size = hw_seg_size;
hw_seg_size = bv->bv_len;
nr_hw_segs++;

nr_phys_segs++;
bvprv = bv;
Expand Down Expand Up @@ -150,23 +142,6 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
return 0;
}

static int blk_hw_contig_segment(struct request_queue *q, struct bio *bio,
struct bio *nxt)
{
if (!bio_flagged(bio, BIO_SEG_VALID))
blk_recount_segments(q, bio);
if (!bio_flagged(nxt, BIO_SEG_VALID))
blk_recount_segments(q, nxt);
if (bio_has_data(bio) &&
(!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size)))
return 0;
if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size)
return 0;

return 1;
}

/*
* map a request to scatterlist, return number of sg entries setup. Caller
* must make sure sg can hold rq->nr_phys_segments entries
Expand Down Expand Up @@ -304,7 +279,6 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
unsigned short max_sectors;
int len;

if (unlikely(blk_pc_request(req)))
max_sectors = q->max_hw_sectors;
Expand All @@ -321,20 +295,6 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
blk_recount_segments(q, req->biotail);
if (!bio_flagged(bio, BIO_SEG_VALID))
blk_recount_segments(q, bio);
len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
if (!bio_has_data(bio) ||
(BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio))
&& !BIOVEC_VIRT_OVERSIZE(len))) {
int mergeable = ll_new_mergeable(q, req, bio);

if (mergeable) {
if (req->nr_hw_segments == 1)
req->bio->bi_hw_front_size = len;
if (bio->bi_hw_segments == 1)
bio->bi_hw_back_size = len;
}
return mergeable;
}

return ll_new_hw_segment(q, req, bio);
}
Expand All @@ -343,7 +303,6 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
unsigned short max_sectors;
int len;

if (unlikely(blk_pc_request(req)))
max_sectors = q->max_hw_sectors;
Expand All @@ -357,24 +316,10 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
q->last_merge = NULL;
return 0;
}
len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
if (!bio_flagged(bio, BIO_SEG_VALID))
blk_recount_segments(q, bio);
if (!bio_flagged(req->bio, BIO_SEG_VALID))
blk_recount_segments(q, req->bio);
if (!bio_has_data(bio) ||
(BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
!BIOVEC_VIRT_OVERSIZE(len))) {
int mergeable = ll_new_mergeable(q, req, bio);

if (mergeable) {
if (bio->bi_hw_segments == 1)
bio->bi_hw_front_size = len;
if (req->nr_hw_segments == 1)
req->biotail->bi_hw_back_size = len;
}
return mergeable;
}

return ll_new_hw_segment(q, req, bio);
}
Expand Down Expand Up @@ -406,18 +351,6 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
return 0;

total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
int len = req->biotail->bi_hw_back_size +
next->bio->bi_hw_front_size;
/*
* propagate the combined length to the end of the requests
*/
if (req->nr_hw_segments == 1)
req->bio->bi_hw_front_size = len;
if (next->nr_hw_segments == 1)
next->biotail->bi_hw_back_size = len;
total_hw_segments--;
}

if (total_hw_segments > q->max_hw_segments)
return 0;
Expand Down
6 changes: 2 additions & 4 deletions fs/bio.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -350,8 +350,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
*/

while (bio->bi_phys_segments >= q->max_phys_segments
|| bio->bi_hw_segments >= q->max_hw_segments
|| BIOVEC_VIRT_OVERSIZE(bio->bi_size)) {
|| bio->bi_hw_segments >= q->max_hw_segments) {

if (retried_segments)
return 0;
Expand Down Expand Up @@ -395,8 +394,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
}

/* If we may be able to merge these biovecs, force a recount */
if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec) ||
BIOVEC_VIRT_MERGEABLE(bvec-1, bvec)))
if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
bio->bi_flags &= ~(1 << BIO_SEG_VALID);

bio->bi_vcnt++;
Expand Down
15 changes: 0 additions & 15 deletions include/linux/bio.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,21 +26,8 @@

#ifdef CONFIG_BLOCK

/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
#include <asm/io.h>

#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
#else
#define BIOVEC_VIRT_START_SIZE(x) 0
#define BIOVEC_VIRT_OVERSIZE(x) 0
#endif

#ifndef BIO_VMERGE_BOUNDARY
#define BIO_VMERGE_BOUNDARY 0
#endif

#define BIO_DEBUG

#ifdef BIO_DEBUG
Expand Down Expand Up @@ -240,8 +227,6 @@ static inline void *bio_data(struct bio *bio)
((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
#endif

#define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \
((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
Expand Down

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