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Commit ac5d156c78a68b39955ee9b09498ba93831c77d7

Authored by Jaegeuk Kim
1 parent b743ba78ae
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

f2fs: modify the number of issued pages to merge IOs 

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>

Showing 3 changed files with 14 additions and 5 deletions Side-by-side Diff

... ... @@ -1171,7 +1171,6 @@
1171 1171 struct writeback_control *wbc)
1172 1172 {
1173 1173 struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
1174   - struct block_device *bdev = sbi->sb->s_bdev;
1175 1174 long nr_to_write = wbc->nr_to_write;
1176 1175  
1177 1176 /* First check balancing cached NAT entries */
1178 1177  
... ... @@ -1185,10 +1184,9 @@
1185 1184 return 0;
1186 1185  
1187 1186 /* if mounting is failed, skip writing node pages */
1188   - wbc->nr_to_write = bio_get_nr_vecs(bdev);
  1187 + wbc->nr_to_write = max_hw_blocks(sbi);
1189 1188 sync_node_pages(sbi, 0, wbc);
1190   - wbc->nr_to_write = nr_to_write -
1191   - (bio_get_nr_vecs(bdev) - wbc->nr_to_write);
  1189 + wbc->nr_to_write = nr_to_write - (max_hw_blocks(sbi) - wbc->nr_to_write);
1192 1190 return 0;
1193 1191 }
1194 1192  
... ... @@ -734,7 +734,7 @@
734 734 do_submit_bio(sbi, type, false);
735 735 alloc_new:
736 736 if (sbi->bio[type] == NULL) {
737   - sbi->bio[type] = f2fs_bio_alloc(bdev, bio_get_nr_vecs(bdev));
  737 + sbi->bio[type] = f2fs_bio_alloc(bdev, max_hw_blocks(sbi));
738 738 sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
739 739 /*
740 740 * The end_io will be assigned at the sumbission phase.
... ... @@ -8,6 +8,8 @@
8 8 * it under the terms of the GNU General Public License version 2 as
9 9 * published by the Free Software Foundation.
10 10 */
  11 +#include <linux/blkdev.h>
  12 +
11 13 /* constant macro */
12 14 #define NULL_SEGNO ((unsigned int)(~0))
13 15 #define NULL_SECNO ((unsigned int)(~0))
... ... @@ -86,6 +88,8 @@
86 88  
87 89 #define SECTOR_FROM_BLOCK(sbi, blk_addr) \
88 90 (blk_addr << ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE))
  91 +#define SECTOR_TO_BLOCK(sbi, sectors) \
  92 + (sectors >> ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE))
89 93  
90 94 /* during checkpoint, bio_private is used to synchronize the last bio */
91 95 struct bio_private {
... ... @@ -623,5 +627,12 @@
623 627 if (IS_CURSEC(sbi, secno) || (sbi->cur_victim_sec == secno))
624 628 return true;
625 629 return false;
  630 +}
  631 +
  632 +static inline unsigned int max_hw_blocks(struct f2fs_sb_info *sbi)
  633 +{
  634 + struct block_device *bdev = sbi->sb->s_bdev;
  635 + struct request_queue *q = bdev_get_queue(bdev);
  636 + return SECTOR_TO_BLOCK(sbi, queue_max_sectors(q));
626 637 }