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f2fs: avoid issuing small bios due to several dirty node pages 

If some small bios of dirty node pages are supposed to be issued during the
sequential data writes, there-in well-produced consecutive data bios are able
to be split by the small node bios, resulting in performance degradation.
So, let's collect a number of dirty node pages until reaching a threshold.
And, by default, I set the threshold as 2MB, a segment size.

This improves sequential write performance on i5, 512GB SSD (830 w/ SATA2) as
follows.
Before: 231 MB/s -> After: 255 MB/s

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
This commit is contained in:
Jaegeuk Kim 2013-01-18 14:54:13 +09:00
parent c01e54b770
commit a7fdffbd3e
1 changed files with 11 additions and 6 deletions
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17
fs/f2fs/node.c
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@ -1124,6 +1124,12 @@ static int f2fs_write_node_page(struct page *page,
return 0;
}
/*
* It is very important to gather dirty pages and write at once, so that we can
* submit a big bio without interfering other data writes.
* Be default, 512 pages (2MB), a segment size, is quite reasonable.
*/
#define COLLECT_DIRTY_NODES 512
static int f2fs_write_node_pages(struct address_space *mapping,
struct writeback_control *wbc)
{
@ -1131,17 +1137,16 @@ static int f2fs_write_node_pages(struct address_space *mapping,
struct block_device *bdev = sbi->sb->s_bdev;
long nr_to_write = wbc->nr_to_write;
if (wbc->for_kupdate)
return 0;
if (get_pages(sbi, F2FS_DIRTY_NODES) == 0)
return 0;
/* First check balancing cached NAT entries */
if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) {
write_checkpoint(sbi, false, false);
return 0;
}
/* collect a number of dirty node pages and write together */
if (get_pages(sbi, F2FS_DIRTY_NODES) < COLLECT_DIRTY_NODES)
return 0;
/* if mounting is failed, skip writing node pages */
wbc->nr_to_write = bio_get_nr_vecs(bdev);
sync_node_pages(sbi, 0, wbc);