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f2fs: modify the number of issued pages to merge IOs

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When testing f2fs on an SSD, I found some 128 page IOs followed by 1 page IO
were issued by f2fs_write_node_pages.
This means that there were some mishandling flows which degrades performance.

Previous f2fs_write_node_pages determines the number of pages to be written,
nr_to_write, as follows.

1. The bio_get_nr_vecs returns 129 pages.
2. The bio_alloc makes a room for 128 pages.
3. The initial 128 pages go into one bio.
4. The existing bio is submitted, and a new bio is prepared for the last 1 page.
5. Finally, sync_node_pages submits the last 1 page bio.

The problem is from the use of bio_get_nr_vecs, so this patch replace it
with max_hw_blocks using queue_max_sectors.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This commit is contained in:
Jaegeuk Kim
2013-04-29 16:58:39 +09:00
parent b743ba78ae
commit ac5d156c78
3 changed files with 14 additions and 5 deletions
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2
fs/f2fs/segment.c
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@@ -734,7 +734,7 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
do_submit_bio(sbi, type, false);
alloc_new:
if (sbi->bio[type] == NULL) {
sbi->bio[type] = f2fs_bio_alloc(bdev, bio_get_nr_vecs(bdev));
sbi->bio[type] = f2fs_bio_alloc(bdev, max_hw_blocks(sbi));
sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
/*
* The end_io will be assigned at the sumbission phase.