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Date: Wed, 13 Nov 2013 11:39:28 +0800
From: Gu Zheng <guz.fnst@...fujitsu.com>
To: Chao Yu <chao2.yu@...sung.com>
CC: ??? <jaegeuk.kim@...sung.com>, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
谭姝 <shu.tan@...sung.com>
Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: read contiguous sit entry pages
by merging for mount performance
Hi Yu,
On 11/12/2013 01:18 PM, Chao Yu wrote:
> Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
> So we read pages as contiguous as possible for better mount performance.
>
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> ---
> fs/f2fs/f2fs.h | 2 ++
> fs/f2fs/segment.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++---
> fs/f2fs/segment.h | 2 ++
> 3 files changed, 66 insertions(+), 3 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 0afdcec..bfe9d87 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1113,6 +1113,8 @@ struct page *find_data_page(struct inode *, pgoff_t, bool);
> struct page *get_lock_data_page(struct inode *, pgoff_t);
> struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
> int f2fs_readpage(struct f2fs_sb_info *, struct page *, block_t, int);
> +void f2fs_submit_read_bio(struct f2fs_sb_info *, int);
> +void submit_read_page(struct f2fs_sb_info *, struct page *, block_t, int);
Better to move these declarations into PATCH 1/2.
> int do_write_data_page(struct page *);
>
> /*
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 86dc289..414c351 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1474,19 +1474,72 @@ static int build_curseg(struct f2fs_sb_info *sbi)
> return restore_curseg_summaries(sbi);
> }
>
> +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
> + int nrpages, bool *is_order)
> +{
> + struct address_space *mapping = sbi->meta_inode->i_mapping;
> + struct sit_info *sit_i = SIT_I(sbi);
> + struct page *page;
> + block_t blk_addr;
> + int blkno, readcnt = 0;
> + int sit_blk_cnt = SIT_BLK_CNT(sbi);
> +
> + for (blkno = start; blkno < start + nrpages; blkno++) {
> +
> + if (blkno >= sit_blk_cnt)
Merge these two judgements:
for (blkno = start; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++)
> + goto out;
> + if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
> + *is_order = !*is_order;
> + goto out;
'Break' seems more suitable.
> + }
> +
> + blk_addr = sit_i->sit_base_addr + blkno;
> + if (*is_order)
> + blk_addr += sit_i->sit_blocks;
> +repeat:
> + page = grab_cache_page(mapping, blk_addr);
> + if (!page) {
> + cond_resched();
> + goto repeat;
> + }
> + if (PageUptodate(page)) {
> + f2fs_put_page(page, 1);
> + readcnt++;
> + goto out;
Here may be 'Continue'.
> + }
> +
> + submit_read_page(sbi, page, blk_addr, READ_SYNC);
> +
> + page_cache_release(page);
Put page here seems not a good idea, otherwise all your work may be in vain.
> + readcnt++;
> + }
> +out:
> + f2fs_submit_read_bio(sbi, READ_SYNC);
> + return readcnt;
> +}
> +
> static void build_sit_entries(struct f2fs_sb_info *sbi)
> {
> struct sit_info *sit_i = SIT_I(sbi);
> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
> struct f2fs_summary_block *sum = curseg->sum_blk;
> - unsigned int start;
> + bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
> + int sit_blk_cnt = SIT_BLK_CNT(sbi);
> + int bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
> + unsigned int i, start, end;
> + unsigned int readed, start_blk = 0;
>
> - for (start = 0; start < TOTAL_SEGS(sbi); start++) {
> +next:
> + readed = ra_sit_pages(sbi, start_blk, bio_blocks, &is_order);
In fact, you know how many blocks that you want to read(SIT_BLK_CNT(sbi)),
so here sit_blk_cnt is more suitable than a MAX one, and it also can make
the logic of ra_sit_pages more simple.
> +
> + start = start_blk * sit_i->sents_per_block;
> + end = (start_blk + readed) * sit_i->sents_per_block;
> +
> + for (; start < end && start < TOTAL_SEGS(sbi); start++) {
> struct seg_entry *se = &sit_i->sentries[start];
> struct f2fs_sit_block *sit_blk;
> struct f2fs_sit_entry sit;
> struct page *page;
> - int i;
>
> mutex_lock(&curseg->curseg_mutex);
> for (i = 0; i < sits_in_cursum(sum); i++) {
> @@ -1497,6 +1550,7 @@ static void build_sit_entries(struct f2fs_sb_info *sbi)
> }
> }
> mutex_unlock(&curseg->curseg_mutex);
> +
> page = get_current_sit_page(sbi, start);
> sit_blk = (struct f2fs_sit_block *)page_address(page);
> sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> @@ -1509,6 +1563,11 @@ got_it:
> e->valid_blocks += se->valid_blocks;
> }
> }
> +
> + start_blk += readed;
> + if (start_blk >= sit_blk_cnt)
> + return;
> + goto next;
Using do {...} while(start_blk < sit_blk_cnt) rather than the so big upstream goto.
> }
>
> static void init_free_segmap(struct f2fs_sb_info *sbi)
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 269f690..ad5b9f1 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -83,6 +83,8 @@
> (segno / SIT_ENTRY_PER_BLOCK)
> #define START_SEGNO(sit_i, segno) \
> (SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
> +#define SIT_BLK_CNT(sbi) \
> + ((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
> #define f2fs_bitmap_size(nr) \
> (BITS_TO_LONGS(nr) * sizeof(unsigned long))
> #define TOTAL_SEGS(sbi) (SM_I(sbi)->main_segments)
--
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