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Message-ID: <20161116191828.GB57609@jaegeuk>
Date: Wed, 16 Nov 2016 11:18:28 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH v3] f2fs: don't wait writeback for datas during checkpoint
Hi Chao,
On Wed, Nov 16, 2016 at 10:41:20AM +0800, Chao Yu wrote:
> Normally, while committing checkpoint, we will wait on all pages to be
> writebacked no matter the page is data or metadata, so in scenario where
> there are lots of data IO being submitted with metadata, we may suffer
> long latency for waiting writeback during checkpoint.
>
> Indeed, we only care about persistence for pages with metadata, but not
> pages with data, as file system consistent are only related to metadate,
> so in order to avoid encountering long latency in above scenario, let's
> recognize and reference metadata in submitted IOs, wait writeback only
> for metadatas.
>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> v3: clean up codes as Jaegeuk suggested.
> fs/f2fs/checkpoint.c | 2 +-
> fs/f2fs/data.c | 37 +++++++++++++++++++++++++++++++------
> fs/f2fs/debug.c | 7 ++++---
> fs/f2fs/f2fs.h | 8 +++++---
> fs/f2fs/file.c | 2 --
> fs/f2fs/gc.c | 2 --
> fs/f2fs/segment.c | 1 -
> 7 files changed, 41 insertions(+), 18 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 7bece59..5039ed8 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -1003,7 +1003,7 @@ static void wait_on_all_pages_writeback(struct f2fs_sb_info *sbi)
> for (;;) {
> prepare_to_wait(&sbi->cp_wait, &wait, TASK_UNINTERRUPTIBLE);
>
> - if (!atomic_read(&sbi->nr_wb_bios))
> + if (!get_pages(sbi, F2FS_WB_CP_DATA))
> break;
>
> io_schedule_timeout(5*HZ);
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 66d2aee..4115689 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -29,6 +29,28 @@
> #include "trace.h"
> #include <trace/events/f2fs.h>
>
> +static bool __is_cp_guaranteed(struct page *page)
> +{
> + struct address_space *mapping = page->mapping;
> + struct inode *inode;
> + struct f2fs_sb_info *sbi;
> +
> + if (!mapping)
> + return false;
> +
> + inode = mapping->host;
> + sbi = F2FS_I_SB(inode);
> +
> + if (inode->i_ino == F2FS_META_INO(sbi) ||
> + inode->i_ino == F2FS_NODE_INO(sbi) ||
> + S_ISDIR(inode->i_mode) ||
> + is_cold_data(page))
> + return true;
> + return false;
> +}
> +
> +#define WB_DATA_TYPE(p) (__is_cp_guaranteed(p) ? F2FS_WB_CP_DATA : F2FS_WB_DATA)
I moved this into f2fs.h.
Thanks,
> +
> static void f2fs_read_end_io(struct bio *bio)
> {
> struct bio_vec *bvec;
> @@ -73,6 +95,7 @@ static void f2fs_write_end_io(struct bio *bio)
>
> bio_for_each_segment_all(bvec, bio, i) {
> struct page *page = bvec->bv_page;
> + enum count_type type = WB_DATA_TYPE(page);
>
> fscrypt_pullback_bio_page(&page, true);
>
> @@ -80,9 +103,11 @@ static void f2fs_write_end_io(struct bio *bio)
> mapping_set_error(page->mapping, -EIO);
> f2fs_stop_checkpoint(sbi, true);
> }
> + dec_page_count(sbi, type);
> + clear_cold_data(page);
> end_page_writeback(page);
> }
> - if (atomic_dec_and_test(&sbi->nr_wb_bios) &&
> + if (!get_pages(sbi, F2FS_WB_CP_DATA) &&
> wq_has_sleeper(&sbi->cp_wait))
> wake_up(&sbi->cp_wait);
>
> @@ -111,7 +136,6 @@ static inline void __submit_bio(struct f2fs_sb_info *sbi,
> struct bio *bio, enum page_type type)
> {
> if (!is_read_io(bio_op(bio))) {
> - atomic_inc(&sbi->nr_wb_bios);
> if (f2fs_sb_mounted_blkzoned(sbi->sb) &&
> current->plug && (type == DATA || type == NODE))
> blk_finish_plug(current->plug);
> @@ -272,6 +296,11 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio)
> verify_block_addr(sbi, fio->old_blkaddr);
> verify_block_addr(sbi, fio->new_blkaddr);
>
> + bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page;
> +
> + if (!is_read)
> + inc_page_count(sbi, WB_DATA_TYPE(bio_page));
> +
> down_write(&io->io_rwsem);
>
> if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 ||
> @@ -284,8 +313,6 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio)
> io->fio = *fio;
> }
>
> - bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page;
> -
> if (bio_add_page(io->bio, bio_page, PAGE_SIZE, 0) <
> PAGE_SIZE) {
> __submit_merged_bio(io);
> @@ -1296,7 +1323,6 @@ static int f2fs_write_data_page(struct page *page,
> if (err && err != -ENOENT)
> goto redirty_out;
>
> - clear_cold_data(page);
> out:
> inode_dec_dirty_pages(inode);
> if (err)
> @@ -1699,7 +1725,6 @@ static int f2fs_write_end(struct file *file,
> goto unlock_out;
>
> set_page_dirty(page);
> - clear_cold_data(page);
>
> if (pos + copied > i_size_read(inode))
> f2fs_i_size_write(inode, pos + copied);
> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> index 2fdf233..67a04d8 100644
> --- a/fs/f2fs/debug.c
> +++ b/fs/f2fs/debug.c
> @@ -50,7 +50,8 @@ static void update_general_status(struct f2fs_sb_info *sbi)
> si->ndirty_files = sbi->ndirty_inode[FILE_INODE];
> si->ndirty_all = sbi->ndirty_inode[DIRTY_META];
> si->inmem_pages = get_pages(sbi, F2FS_INMEM_PAGES);
> - si->wb_bios = atomic_read(&sbi->nr_wb_bios);
> + si->nr_wb_cp_data = get_pages(sbi, F2FS_WB_CP_DATA);
> + si->nr_wb_data = get_pages(sbi, F2FS_WB_DATA);
> si->total_count = (int)sbi->user_block_count / sbi->blocks_per_seg;
> si->rsvd_segs = reserved_segments(sbi);
> si->overp_segs = overprovision_segments(sbi);
> @@ -313,8 +314,8 @@ static int stat_show(struct seq_file *s, void *v)
> seq_printf(s, " - Inner Struct Count: tree: %d(%d), node: %d\n",
> si->ext_tree, si->zombie_tree, si->ext_node);
> seq_puts(s, "\nBalancing F2FS Async:\n");
> - seq_printf(s, " - inmem: %4d, wb_bios: %4d\n",
> - si->inmem_pages, si->wb_bios);
> + seq_printf(s, " - inmem: %4d, wb_cp_data: %4d, wb_data: %4d\n",
> + si->inmem_pages, si->nr_wb_cp_data, si->nr_wb_data);
> seq_printf(s, " - nodes: %4d in %4d\n",
> si->ndirty_node, si->node_pages);
> seq_printf(s, " - dents: %4d in dirs:%4d (%4d)\n",
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f264c1b..34405dc 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -682,6 +682,8 @@ enum count_type {
> F2FS_DIRTY_META,
> F2FS_INMEM_PAGES,
> F2FS_DIRTY_IMETA,
> + F2FS_WB_CP_DATA,
> + F2FS_WB_DATA,
> NR_COUNT_TYPE,
> };
>
> @@ -849,7 +851,6 @@ struct f2fs_sb_info {
> block_t discard_blks; /* discard command candidats */
> block_t last_valid_block_count; /* for recovery */
> u32 s_next_generation; /* for NFS support */
> - atomic_t nr_wb_bios; /* # of writeback bios */
>
> /* # of pages, see count_type */
> atomic_t nr_pages[NR_COUNT_TYPE];
> @@ -1263,7 +1264,8 @@ static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
> {
> atomic_inc(&sbi->nr_pages[count_type]);
>
> - if (count_type == F2FS_DIRTY_DATA || count_type == F2FS_INMEM_PAGES)
> + if (count_type == F2FS_DIRTY_DATA || count_type == F2FS_INMEM_PAGES ||
> + count_type == F2FS_WB_CP_DATA || count_type == F2FS_WB_DATA)
> return;
>
> set_sbi_flag(sbi, SBI_IS_DIRTY);
> @@ -2219,7 +2221,7 @@ struct f2fs_stat_info {
> unsigned int ndirty_dirs, ndirty_files, ndirty_all;
> int nats, dirty_nats, sits, dirty_sits, free_nids, alloc_nids;
> int total_count, utilization;
> - int bg_gc, wb_bios;
> + int bg_gc, nr_wb_cp_data, nr_wb_data;
> int inline_xattr, inline_inode, inline_dir, orphans;
> unsigned int valid_count, valid_node_count, valid_inode_count, discard_blks;
> unsigned int bimodal, avg_vblocks;
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index e821c39..dd1c5c3 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -96,8 +96,6 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
> if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
> f2fs_wait_on_encrypted_page_writeback(sbi, dn.data_blkaddr);
>
> - /* if gced page is attached, don't write to cold segment */
> - clear_cold_data(page);
> out:
> sb_end_pagefault(inode->i_sb);
> f2fs_update_time(sbi, REQ_TIME);
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 11ff05e..c4b3c32 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -695,8 +695,6 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> congestion_wait(BLK_RW_ASYNC, HZ/50);
> goto retry;
> }
> -
> - clear_cold_data(page);
> }
> out:
> f2fs_put_page(page, 1);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 078c571..d8aa703 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -290,7 +290,6 @@ static int __commit_inmem_pages(struct inode *inode,
> /* record old blkaddr for revoking */
> cur->old_addr = fio.old_blkaddr;
>
> - clear_cold_data(page);
> submit_bio = true;
> }
> unlock_page(page);
> --
> 2.8.2.311.gee88674
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