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Date: Thu, 21 Nov 2013 10:31:57 +0900
From: Jaegeuk Kim <jaegeuk.kim@...sung.com>
To: Chao Yu <chao2.yu@...sung.com>
Cc: 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 V2 2/2 RESEND] f2fs: read contiguous sit entry
pages by merging for mount performance
Hi,
It seems that ra_sit_pages() is too tightly coupled with
build_sit_entries().
Is there another way not to use *is_order?
The ra_sit_pages() tries to read consecutive sit pages as many as
possible.
So then, what about just checking whether its block address is
contiguous or not?
Something like this:
-ra_sit_pages()
blkno = start;
while (blkno < sit_i->sit_blocks) {
blk_addr = current_sit_addr(sbi, blkno);
if (blkno != start && prev_blk_addr + 1 != blk_addr)
break;
/* grab and submit_read_page */
prev_blk_addr = blk_addr;
blkno++;
}
Thanks,
2013-11-20 (수), 14:47 +0800, Chao Yu:
> 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.
>
> v1-->v2:
> o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng
> suggested.
> o add mark_page_accessed() before release page to delay VM reclaiming them.
>
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> ---
> fs/f2fs/segment.c | 108 ++++++++++++++++++++++++++++++++++++++++-------------
> fs/f2fs/segment.h | 2 +
> 2 files changed, 84 insertions(+), 26 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8149eba..52c88de 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -14,6 +14,7 @@
> #include <linux/blkdev.h>
> #include <linux/prefetch.h>
> #include <linux/vmalloc.h>
> +#include <linux/swap.h>
>
> #include "f2fs.h"
> #include "segment.h"
> @@ -1488,41 +1489,96 @@ 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)
Why do you use nrpages?
> +{
> + 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 = start, readcnt = 0;
> + int sit_blk_cnt = SIT_BLK_CNT(sbi);
> +
> + for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
> +
> + if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
> + *is_order = !*is_order;
> + break;
> + }
> +
> + 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)) {
> + mark_page_accessed(page);
> + f2fs_put_page(page, 1);
> + readcnt++;
> + continue;
> + }
> +
> + submit_read_page(sbi, page, blk_addr, READ_SYNC);
> +
> + mark_page_accessed(page);
> + f2fs_put_page(page, 0);
> + readcnt++;
> + }
> +
> + 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;
> -
> - for (start = 0; 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;
> + bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
> + int sit_blk_cnt = SIT_BLK_CNT(sbi);
> + unsigned int i, start, end;
> + unsigned int readed, start_blk = 0;
>
> - mutex_lock(&curseg->curseg_mutex);
> - for (i = 0; i < sits_in_cursum(sum); i++) {
> - if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> - sit = sit_in_journal(sum, i);
> - mutex_unlock(&curseg->curseg_mutex);
> - goto got_it;
> + do {
> + readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
> +
> + 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;
> +
> + mutex_lock(&curseg->curseg_mutex);
> + for (i = 0; i < sits_in_cursum(sum); i++) {
> + if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> + sit = sit_in_journal(sum, i);
> + mutex_unlock(&curseg->curseg_mutex);
> + goto got_it;
> + }
> }
> - }
> - 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)];
> - f2fs_put_page(page, 1);
> + 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)];
> + f2fs_put_page(page, 1);
> got_it:
> - check_block_count(sbi, start, &sit);
> - seg_info_from_raw_sit(se, &sit);
> - if (sbi->segs_per_sec > 1) {
> - struct sec_entry *e = get_sec_entry(sbi, start);
> - e->valid_blocks += se->valid_blocks;
> + check_block_count(sbi, start, &sit);
> + seg_info_from_raw_sit(se, &sit);
> + if (sbi->segs_per_sec > 1) {
> + struct sec_entry *e = get_sec_entry(sbi, start);
> + e->valid_blocks += se->valid_blocks;
> + }
> }
> - }
> + start_blk += readed;
> + } while (start_blk < sit_blk_cnt);
> }
>
> 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)
--
Jaegeuk Kim
Samsung
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