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Commit 225311a4 authored by Huang Ying's avatar Huang Ying Committed by Linus Torvalds
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mm: test code to write THP to swap device as a whole 

To support delay splitting THP (Transparent Huge Page) after swapped
out, we need to enhance swap writing code to support to write a THP as a
whole.  This will improve swap write IO performance.

As Ming Lei <ming.lei@redhat.com> pointed out, this should be based on
multipage bvec support, which hasn't been merged yet.  So this patch is
only for testing the functionality of the other patches in the series.
And will be reimplemented after multipage bvec support is merged.

Link: http://lkml.kernel.org/r/20170724051840.2309-7-ying.huang@intel.com


Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c]
Cc: Shaohua Li <shli@kernel.org>
Cc: Vishal L Verma <vishal.l.verma@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 98cc093c

include/linux/bio.h

+8 −0
Original line number Diff line number Diff line
@@ -38,7 +38,15 @@ 
#define BIO_BUG_ON

#endif



#ifdef CONFIG_THP_SWAP

#if HPAGE_PMD_NR > 256

#define BIO_MAX_PAGES		HPAGE_PMD_NR

#else

#define BIO_MAX_PAGES		256

#endif

#else

#define BIO_MAX_PAGES		256

#endif



#define bio_prio(bio)			(bio)->bi_ioprio

#define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)

include/linux/page-flags.h

+2 −2
Original line number Diff line number Diff line
@@ -303,8 +303,8 @@ PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 
 * Only test-and-set exist for PG_writeback.  The unconditional operators are

 * risky: they bypass page accounting.

 */

TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)

	TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)

TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)

	TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)

PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)



/* PG_readahead is only used for reads; PG_reclaim is only for writes */

include/linux/vm_event_item.h

+1 −0
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, 
#endif

		THP_ZERO_PAGE_ALLOC,

		THP_ZERO_PAGE_ALLOC_FAILED,

		THP_SWPOUT,

#endif

#ifdef CONFIG_MEMORY_BALLOON

		BALLOON_INFLATE,

mm/page_io.c

+16 −5
Original line number Diff line number Diff line
@@ -28,16 +28,18 @@ 
static struct bio *get_swap_bio(gfp_t gfp_flags,

				struct page *page, bio_end_io_t end_io)

{

	int i, nr = hpage_nr_pages(page);

	struct bio *bio;



	bio = bio_alloc(gfp_flags, 1);

	bio = bio_alloc(gfp_flags, nr);

	if (bio) {

		bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);

		bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;

		bio->bi_end_io = end_io;



		bio_add_page(bio, page, PAGE_SIZE, 0);

		BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE);

		for (i = 0; i < nr; i++)

			bio_add_page(bio, page + i, PAGE_SIZE, 0);

		VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr);

	}

	return bio;

}
@@ -262,6 +264,15 @@ static sector_t swap_page_sector(struct page *page) 
	return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);

}



static inline void count_swpout_vm_event(struct page *page)

{

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	if (unlikely(PageTransHuge(page)))

		count_vm_event(THP_SWPOUT);

#endif

	count_vm_events(PSWPOUT, hpage_nr_pages(page));

}



int __swap_writepage(struct page *page, struct writeback_control *wbc,

		bio_end_io_t end_write_func)

{
@@ -313,7 +324,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc, 


	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);

	if (!ret) {

		count_vm_event(PSWPOUT);

		count_swpout_vm_event(page);

		return 0;

	}
@@ -326,7 +337,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc, 
		goto out;

	}

	bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);

	count_vm_event(PSWPOUT);

	count_swpout_vm_event(page);

	set_page_writeback(page);

	unlock_page(page);

	submit_bio(bio);

mm/vmstat.c

+1 −0
Original line number Diff line number Diff line
@@ -1071,6 +1071,7 @@ const char * const vmstat_text[] = { 
#endif

	"thp_zero_page_alloc",

	"thp_zero_page_alloc_failed",

	"thp_swpout",

#endif

#ifdef CONFIG_MEMORY_BALLOON

	"balloon_inflate",